Fire Code

Explanations & Illustrations

Structural fire precautions relate to the integrity and stability of building elements during fire for a required period of time. “Structural” does not only apply to the structural elements of buildings but other building components, e.g. doors, shafts, walls/ceiling finishes.

The objectives of structural fire precautions are:

1. to unload the spread of fire between adjoining buildings by adequate separation;

2. to prevent the untimely collapse of building, including walls and floors of each unit in the event of a fire; and

3. to prevent spread of fire from one unit to another within the building envelope by compartmentalising each unit with walls, floors and doors having the requisite fire resistance rating.

Explanations & Illustrations

Generally, the compartment size of apartment or maisonette unit would not exceed 4000m² or a cubical extent of 15000m³ as given in Table 3.2A which is reproduced below:

However, for non-residential areas in buildings under PG II, such as communal area or car parking area irrespective of location in either upper storeys or basement, there would be a need to apply the size limitation of 4000m² or 15000m³. The above non-residential areas would be dealt with under their respective PG VII & VIII respectively.

Compartment below ground level

1. Under Table 3.2A no compartment shall comprise more than one storey and exceed floor area of 2000m² and a cubical extent of 7500m³. However, exceptions are allowed in the following situations:

   1. Only 1st basement having a floor area of less than 100m² can form part of the 1^st and upper storey compartment under Cl.3.2.5c., provided the building is sprinkler-protected including the basement.

   2. Basement floors can be interconnected for use as car parking, if sprinkler system is provided.

2. Basement floor or compartment shall not be used for bulk storage of highly inflammable liquids or substances of any explosive nature.

Compartments between average ground level & a height of 24m

No compartment shall comprise more than 3 storeys and floor area greater than 4000m² and cubical extent exceeding 15000m³. However, exceptions are allowed under Cl.3.2.3, Cl.3.2.4a. and Cl.3.2.8.

Compartments above a height of 24m from averaged ground level

1. No compartment shall comprise more than 3 storeys and floor area greater than 4000m² and cubical extent exceeding 15000m³. Every storey above a height of 24m shall be a fire compartment.

   General: In computing the extent of a compartment, protected shafts e.g. lift, staircases etc. and separately compartmented lavatory/locker room can be disregarded. See Cl.1.4.29 for further illustration.

2. High bay warehouse (HBW) and mechanised car parking buildings are treated differently from normal industrial buildings.

The requirement of restricting the compartment to max. 3 storeys would not be applicable. Such types of buildings are usually not occupied or have very limited people working in the premises.

Automatic sprinkler system and smoke extraction or venting system are required to be provided for high bay warehouses and mechanised car parking buildings which exceed 24m in building height.

Compartments above a height of 24m from averaged ground level

No compartment shall comprise more than one storey and exceed the floor area of 2000m² and cubical extent of 7500m³.

This requirement would not apply to high bay warehouses and mechanised car parking buildings. Prior consent is to be obtained from the SCDF before submission of building plan.

Explanations & Illustrations

To avoid providing fire compartmentation in building to comply with the cubical extent and floor area control under Table 3.2A, automatic sprinkler system would be proposed as an alternative. Where automatic sprinkler system is to be provided to a building, compliance with Table 3.2A on max 3 storeys per compartment is still required, unless atrium design is proposed subject to obtaining the SCDF ’s prior approval before submission of building plan.

Explanations & Illustrations

Clause 3.2.4a. : Compartmentation by height

Where 3 storeys or levels form one compartment, the total floor area shall not exceed 4000m² and the total cubical extent shall not exceed 15000m³, subject to compliance with travel distance requirements under Chapter 2.

In the case of atrium design space, it can go beyond 3 storeys per compartment but shall not exceed habitable height of 24m. in other words, every storey beyond 24m in height is a fire compartment.

Clause 3.2.4b. : Compartmentation by height

In any commercial building which exceeds 24m in habitable height, no compartment shall comprise more than one storey per compartment from storey level exceeding 24m above average ground level. There is a need to keep the fire compartment size small within 2000m² or 7500m³ above that habitable height, as it would otherwise pose difficulties to firefighting and control of fire spread should there be a fire occurrence in one of those high-rise units.

In any residential building which exceeds 24m in habitable height, no compartment shall comprise more than one storey per compartment from storey level exceeding 24m above average ground level. However, for residential maisonette or penthouse unit, maximum two storey levels are allowed to form one compartment. This should be taken as a relaxation. There is a need to keep the fire compartment size small within 2000m² or 7500m³ above that habitable height as it would otherwise pose difficulties to fire fighting and control of fire spread should there be a fire occurrence in one of those high-rise units. In situation where there are maisonette or penthouse units located in non-residential building, fire protection/detection system applicable to the building shall be extended to cover the residential units.

Explanations & Illustrations

Clause 3.2.5a. : Areas requiring compartmentation

Explanations & Illustrations

Clause 3.2.5b. : Areas requiring compartmentation

Compartment walls and floors shall be constructed of non-combustible materials to have minimum 1-hr fire resistance rating under Table 3.3A for any of the compartment.

In the above diagram, the car park (PG VIII) is fire compartmented from the shopping area. The car park has higher fire risks than shopping and cineplex. Fire separation between cineplex and shopping area is required. This is to safeguard the occupants in the cineplex from any fire occurrence in the shopping area.

The above diagram shows a typical shopping floor, which has a mixture of different purpose groups without fire compartmentation.

Strictly interpreting the above subclause would mean that in a shopping centre, for example, shop (PG V), office (PG IV), place of public resort (PG VII), commercial school (PG III) would need to be separately compartmented from each other. This would not be practical. In practice, shopping or commercial buildings would have mixture of the uses of different purpose groups.

Under sub-clause (b)(i), an ancillary office which is located within the compartment or floor used as PG V is not required to be separately fire compartmented, provided the measurement of travel distance requirements of PG III shall apply to the ancillary office. Similarly, under sub-clause (b)(ii) , ancillary usage to PG III such as sick/first aid room, reception lobby/area, waiting area, staff lounge/staff recreation room, staff rest room/pantry, staff changing/locker room, meeting room, staff training room, etc. is not required to be separately fire compartmented.

Explanations & Illustrations

Clause 3.2.5c.(2) : Areas requiring compartmentation

To avoid providing fire compartmentation in building to comply with the cubical extent and floor area control under Table 3.2A, automatic sprinkler system would be proposed as an alternative. Where automatic sprinkler system is to be provided to a building, compliance with Table 3.2A on max 3 storeys per compartment is still required, unless atrium design is proposed subject to obtaining the SCDF ’s prior approval before submission of building plan.

Where the floor area of the basement exceeds 100m² it shall be a compartment below ground level and shall not comprise more than one storey. The basement floor shall be provided with sprinkler system under Cl.6.4.1d.(1) and dry riser under Cl.6.2.1b.

In situation where the basement floor area is not exceeding 100m², the basement and upper storeys may be allowed to be interconnected to form one compartment, subject to max. 3 storeys or levels in a single compartment. It should be noted that  Cl.3.2.5d. prohibits more than one storey below ground level to be connected to form one compartment.

All basement floors, except those under PG I & II, are required to be provided with automatic sprinkler system under Cl.6.4.1d.(1). Where basement floor, regardless of its area, is interconnected with upper storeys, the automatic sprinkler system required for the basement shall be extended to cover all the upper storeys.

For buildings under PG IV, V and VII, the first basement floor can be inter-connected with the upper storeys regardless of whether or not it exceeds 100m², provided sprinkler system and smoke control system are provided.  For atrium design, prior consent from the SCDF should be obtained before making Building Plan submission.  See Cl.3.2.4a..

Cl.3.2.5d. prohibits more than one basement floor to be connected to form one compartment, except in the case of basement used solely for car parking.

Explanations & Illustrations

Clause 3.2.5d. : Areas requiring compartmentation

Basement 1, which has a floor area of less than 100m² can be interconnected with 1st storey, provided it is compartmented from basement 2. Sprinkler system and rising mains are required to be provided to the building.

Basement 1 having a floor area of more than 100m² is required to be compartmented from 1st storey. The above clause does not permit more than one basement storey per compartment unless solely used for car parking. Sprinkler system and rising main are required to be provided to basement.

Owing to the special use where ramps or car lifts are needed to connect all the floors, compartmentation is relaxed where sprinkler system and rising main are provided.

Explanations & Illustrations

Clause 3.2.5e. : Areas requiring compartmentation

The fire resistance rating of the walls and floors shall comply with the elements of structure and shall have minimum period of 2 hours. Any door opening into the Fire Command Centre from the occupancy area shall be minimum 2-hr fire-rated.

Explanations & Illustrations

Clause 3.2.5f.(1)(a) : Areas requiring compartmentation

The above sub clause allows the kitchen not to be compartmented if the cooking hood or range is installed with an automatic fire suppression system. Automatic fire suppression system shall be of approved type based on international standards such as NFPA 17A. QPs are also reminded to ensure that the premise owners/ operators are aware of the stipulated maintenance regime in the standards.

With this arrangement, there is no need to seek waiver approval from the SCDF.

Clause 3.2.5f.(1)(b) : Areas requiring compartmentation

Clause 3.2.5f.(1)(c) : Areas requiring compartmentation

The 25% and 50% ventilation openings are required for smoke venting and relief of accumulated heat from the area on fire. This exemption cannot be applied in an enclosed air-conditioned environment, where the peripheral walls are fitted with glass panel.

The 25% and 50% ventilation openings are absolute values. Extrapolation of percentage ventilation openings based on depth of the eating establishment is not permitted.

In the above figure the kitchens are not required to be compartmented.

Ventilation openings along the external walls ‘a’, ‘b’, ‘c’ and ‘d’ shall be uninterrupted, having minimum 50% of the perimeter walls of the eating establishment. The openings to the air well shall not be included in this purpose.

The above requirement is more relevant to hawker centre type design.

Clause 3.2.5f.(1)(d) : Areas requiring compartmentation

Under Cl.3.2.5f.(1)(d)(i), the kitchen and dining area can be in one compartment, provided the building is sprinkler-protected and there is no need restricting to the floor area of the compartment

With the provision of sprinkler system, further relaxation is allowed to permit the whole eating establishment to be enclosed with at least 1-hr fire-rated walls and ½-hr fire-rated door. There is no restriction to the accessible floor area of the eating establishments.

Under Cl.3.2.5f.(1)(d)(ii), where the building is not sprinkler-protected, the area of the compartment, kitchen and dining area e.g. (unit A) shall not exceed 150m².

Explanations & Illustrations

Clause 3.2.5f.(1) to (3) : Areas requiring compartmentation

The above figure illustrates a eating establishment without kitchen fire-suppression system.  The clause enables the QP to exercise the option of compartmenting kitchen with open-flame cooking.

Kitchen is compartmented from dining area by 1-hr enclosures and ½-hr fire doors. Protection to servery hatch can be a fire-rated roller shutter held in the open position by fusible links.

As the dumb waiter is connecting 2 storeys, it shall be enclosed in 2-hr protective enclosures with 1-hr fire-rated access door at each storey.

Explanations & Illustrations

Clause 3.2.5f.(4) : Areas requiring compartmentation

Kitchen is required to be compartmented from other areas by 1-hr compartment walls and floors. Doors to the kitchen shall have minimum ½-hr fire resistance rating and shall open outward from the kitchen. Small fires which commonly occur in the kitchen are often caused by overheating of cooking oil on the stove or in a deep pan fryer or by grill. Exhaust ducts in kitchen are usually coated with grease internally over a period of time. Fire in the ducts could be started by sparks or by fire from the stove.

Cooking appliances include – open-flame gas fired oven, charcoal grill and appliances which have open flames located or protected from views.

Fire-rated door to kitchen shall not be wedged open for serving purpose. In circumstances where fire doors are to be kept open, the door shall be fitted with electromechanical device susceptible to smoke under Cl.3.9.2c.. See Cl.1.4.34 for further illustration. 

To qualify for non-provision of fire compartment under Cl.3.2.5f.(1), auto fire suppression equipment should be incorporated into the cooking range. This equipment may consist of fixed pipe carbon dioxide, dry chemical or foam- water sprinkler or spray system. Such auto suppression system to the cooking range shall be listed and approved by a certification body.

Explanations & Illustrations

Clause 3.2.5f. : Areas requiring compartmentation

Where ‘open-flame’ cooking is used, the compartment comprising dining and kitchen areas shall not comprise more than one storey:

In the case of eating establishment which comprises 2 storeys, then each storey shall be a fire compartment by itself.

Explanations & Illustrations

Clause 3.2.5g. : Areas requiring compartmentation

Explanations & Illustrations

Clause 3.2.5h. : Areas requiring compartmentation

Spray painting booth or room shall be mechanically ventilated and enclosed in min. 2-hr fire-rated compartment to allow spraying of paint to be carried out. It shall be constructed to prevent the escape of spray and flammable vapour which shall be removed by the exhaust system. 

The exhaust discharge point shall be not less than 5m from the inlet of any mechanical ventilation system.

Explanations & Illustrations

Clause 3.2.5i. : Areas requiring compartmentation

Store 1 exceeding 10m² inside a Hotel space will need to be compartmentalised with 1- hour fire rated enclosures.

Store 2 which is less than 10m² still required to be provided with fire door as the store opens into internal corridor, which is pressurised.

The main reason for compartmentation of storeroom is to prevent undetected fire in the storeroom from developing into a big fire.

Compactus

Compactus room which is more than 10m² shall be treated as a compartment under the above sub-clause. The enclosing walls/floor/ceiling/door shall have min. 1-hr fire resistance rating. Irrespective of the location of the compactus storage area, if it is not enclosed in a room, it shall be treated as open storage shelves and not as a store. The main reason is that a fire occurring in a room could be unnoticed, until it becomes too big to be put out by first aid firefighting equipment. An incipient fire occurring in an unenclosed compactus storage area could be easily spotted by occupants and immediate reaction could be taken to put out the fire.

Any store, regardless of its size, shall be compartmented under the above sub-clause if it opens directly into exit passageways and designated protected escape routes, e.g. smoke-stop lobbies, protected staircases.

Explanations & Illustrations

Clause 3.2.5j. : Areas requiring compartmentation

Transformer and generator rooms that contain flammable liquids should be located against an external wall for external ventilation and explosion relief.

Transformer room

Transformers could be dry type or oil cooled type. Oil cooled type is to be located against an external wall above ground level to allow for external ventilation and explosion relief. Adequate precautions should be taken by the provision of a suitable catch pit or other means to prevent the spread of fire resulting from leakage and ignition of oil.

Generator rooms

Generator sets shall be located in clean, dry locations within fire-rated compartments. They may be placed outdoors if they are of purpose built type, provided proper separation from unprotected openings of the building is maintained. Generator rooms shall be located against an external wall above ground level to allow for external ventilation and explosion relief.

Storage areas of highly combustible or flammable materials

Where possible, oil storage tanks should be installed in open air at ground level at least 6m from adjacent buildings and in accordance with CP 40. A max. capacity of 700 litres of diesel oil is permitted to be stored in the generator room. The oil drum(s) shall be located within a bunded area, capable of containing 100% spillage from the drum(s).

Prior approval is to be obtained from the SCDF for storage of combustible or flammable liquids, other than in the generator room, before building plan submission.

Explanations & Illustrations

1. The above clause allows the SCDF  to vary the max. floor area/cubical extent of fire compartment to allow more than 3 storeys to be interconnected. The critical points for consideration would include the size and configuration of atrium void and the provision of sprinkler system and engineered smoke control system.

2. QPs should consult the SCDF  in cases of all atrium designs before making building plan submission. The vetting will confine only to looking at the concept and the layout and profile of atrium void in the building proposal only. Calculations for the engineered smoke control system shall be submitted separately by M&E QPs.

3. Where a compartment in a building has a total floor area and cubical extent greater than that allowed under Table 3.2A, but the number of floor interconnected by void does not exceed 3 floors, QPs should consult the SCDF whether there is a need to provide engineered smoke control system, before making building plan submission. Similarly, if a compartment in a building has a total floor area and cubical extent greater than that allowed under Table 3.2A and the number of floor interconnected by void is more than 3 floors, QPs should consult the SCDF before making building plan submission. The consultation would confine to vetting of requirements mentioned in sub-clause 2. above.

Atrium design allows multiple floors to be connected beyond 3 storeys per compartment but limit to a  habitable height of 24m. The design would require the provision of engineered smoke control system and sprinkler system. The above clause allows atrium design in buildings, but prior approval from the SCDF must be obtained before building plan submission can be made. See Cl.1.4.13.

Explanations & Illustrations

1. Warehouse compartments A, B & C, as shown in above figure, shall not exceed 2000m² and 7500m³. Each compartment shall comprise one storey only. The materials to be stored in the warehouses shall exclude those listed under Cl.3.2.7c.(1) & (2).

2. Buildings with habitable height not exceeding 24m are allowed to be used for bulk storage of goods or substances of highly combustible nature, except those listed under Cl.3.2.7c.(1) &  (2). However, if the above mentioned warehouse buildings exceed the habitable height of 24m, the whole building must be protected with automatic sprinkler system. Irrespective of the building height, Cl.3.2.7a. shall be complied with.

3. Materials as listed under Cl.3.2.7c.(1) &  (2) are not allowed to be stored in any multi-storey building, regardless of the habitable height.

Explanations & Illustrations

As the habitable height is less than 24m, automatic sprinkler system is not required. The clear width of the air well shall not be less than 2000mm to prevent fire from a car from spreading vertically between split levels. Provision of fire alarm system shall be in accordance with Table 6.3A of the Fire Code.

Openings such as grille, fixed louvre types are considered acceptable. In determining the openings for the grille, obstacle should be deducted to obtain the nett openings. As for fixed louvres, only free area should be taking into account. Provision of sliding windows is not acceptable. The minimum 50% openings in the external walls shall be permanently open and such openings shall be evenly distributed to provide cross ventilation so as to prevent smoke logging.

Situation 1 – Car park is integrated with office/shop building

The attached multi-storey car park is required to be protected by sprinkler system. Cl.3.2.8a. would not apply as there is free access between car park area and the shop/office floor area. There could be sharing of common escape staircases by occupants in the car park area and the shop/office floor area.

Situation 2 – Attached multi-storey car park is an independent building

Attached multi-storey car park would qualify for exemption on size limitation of compartment under Cl.3.2.8a., provided there is no access opening in the continuous vertical compartment wall that separates car park building from shop/office building and no sharing of escape staircases. Each building is self-sufficient in its provision of means of escape. Multi-storey car park shall comply fully with Cl.3.2.8a. on the provision of permanent ventilation openings for cross-ventilation.

Explanations & Illustrations

For the benefit of clarification, the Code has introduced this clause to clarify that the separation material for spaces undergoing additions and other occupied spaces need not be fire-rated construction. Instead, non-combustible partition used for separation between the undergoing A&A works and other occupied areas shall suffice.

Explanations & Illustrations

Any reference to a building, which is divided into compartments, of which an element of structure forms a part, means that compartment of the building (Building A).

Any reference to a building of which an element of structure forms a part means the building (Building B). It is important to note that any element carrying another element of structure must have at least the same fire resistance as the element it is supporting.

Explanations & Illustrations

The continuous vertical compartment wall divides the building into 2 parts. For building A, any reference to height means the building height (A). For building B, any reference to height means the building height (B).

Explanations & Illustrations

The diagram above shows a shopping podium and an office tower. The fire resistance of the elements of structure at the interface between the podium and tower shall be the higher of the two purpose groups (shops or offices).

The elements of structure referred to include compartment floor and also the columns going through the podium to support the structural frame of the office tower.

In the above figures, the continuous vertical compartment wall forms part of more than one building or compartment. The compartment wall shall be constructed to have higher fire resistance rating of the two buildings or compartments.

Explanations & Illustrations

The above figure shows the construction of a non-load-bearing fire-rated compartment wall. If the C-channel or horizontal channel supports are replaced with timber members, the construction would not meet the requirement of the above subclause, as timber members are combustible. However, combustible finish if added to the surface of the wall would be considered as acceptable, provided it complies with Cl.3.13.

The above figure shows the addition of timber floor finish to the R.C floor. The combustible floor finish is not to be considered as contributing to the fire resistance of the floor.

For fire protection to suspended ceilings see Cl.3.3.5. The above clause is also not applicable to buildings under preservation or conservation where structural timber members are required to be retained. See also Cl.9.1.1b. and  Cl.9.9.1.

Explanations & Illustrations

Any part of a non-load-bearing external wall which constitute the unprotected opening in pursuance to Cl.3.5, is not required to have any fire resistance. In the above diagram, the non-load-bearing external wall facing the public road need not have fire resistance as it meets Cl.3.5 on set-back requirement, measured from the centre of the public road to the external wall.

Explanations & Illustrations

The above exemption applies to all single storey buildings. However, in cases where the floor area of the building exceeds 4000m², prior consultation with the SCDF is required.

1. The structural frame or beams and columns of a single storey building need not have fire resistance under Table 3.3A, unless otherwise specified by the SCDF. The QPs shall, before making building plan submission, consult the SCDF as to the need for protection of beams and columns in the following situations :

   1. Single storey factory or warehouse involving high hazard materials;

   2. Single storey factory or warehouse having an extensive footprint; and

   3. Single storey warehouse exceeding a building height of 10m.

2. However, any beam or column which is within or forms part of a compartment wall, separating wall or external wall (which requires fire resistance under Cl.3.5) shall be required to have the same fire resistance rating as the wall in which such beam or column forms part of.

3. Any column or beam which gives support to a wall or gallery, shall have the same fire resistance as that required for the wall or gallery, e.g. column and beam supporting the external wall or mezzanine floor shall have the necessary fire resistance rating.

Explanations & Illustrations

An internal load-bearing wall or a load-bearing part of a wall is not required to have fire resistance under Table 3.3A, provided the wall is not:

1. forming part of or a compartment or separating wall,

2. forming part of the structure enclosing a protected shaft e.g. exit staircase, or

3. supporting a gallery.

Explanations & Illustrations

External wall which does not support a gallery and has adequate setback from the boundary in accordance with Cl.3.5 to be an unprotected area need not have fire resistance under Table 3.3A.

Explanations & Illustrations

Clause 3.3.4 : Exemption for single-storey building

Exemption for Single Storey Buildings

Irrespective of floor area, the minimum period of fire resistance rating for elements of structures is 1 hour. However, Cl.3.3.4 of the current Fire Code provides exemption for single storey buildings which need not comply with 1 hour fire resistance rating for the structural frame or beam or column subject to:

1. the beams or columns are not supporting a wall or gallery;

2. the beams or columns are not forming part of the separating wall between houses;

3. the external walls including the supporting beams or columns which are not supporting a gallery or in  accordance with Cl.3.5 be an unprotected area.

Explanations & Illustrations

The suspended ceiling is to be treated as the soffit as the floor system or assembly consists of the timber boarding, joists and the suspended ceiling to achieve the necessary fire resistance rating. 

Therefore the concealed space in the floor system or assembly is to be treated differently from concealed spaces mentioned under Cl.3.11. The main different is that concealed spaces in floor system or assembly are not permitted to have services such as air-con ducts, cables, pipes etc.; even if these services are housed in fire-rated enclosures.

The implications of Cl.3.3.5 are that the normal type of suspended ceiling consisting of separate tiles cannot be counted as contributing to the fire resistance of the floor in buildings over 15m high where the period required is 1 hour; or in buildings of any height where the period required is more than one hour. In these circumstances only jointless ceilings can be considered as contributing

The above figure shows a protective ceiling being added to the underside of a timber floor, shall apply only to buildings under conservation where retention of the timber floor is required, and in buildings under PG I & II for the construction of attic. In addition to the four grades of ceiling given in Table 3.3B, other ceiling construction to tested prototype listed in the product listing scheme would be considered as acceptable.

The ceiling shown in Figure 3.3.5 - 1, shall be constructed specifically as a fire protecting membrane and comply with Table 3.3B on limitation of fire protecting suspended ceiling. As the ceiling is intended as a protecting membrane, the concealed ceiling space shall not be used for recessed lighting and other service, such as air-con ducts, cables, pipes etc., even if these services are housed in fire-rated enclosures.

Suspended ceilings which are contributing to the fire resistance rating of the floor under Table 3.3B.

The foregoing figures illustrate the intent of the clause which basically deals with the contribution by suspended ceilings to the fire resistance of floors. The provision of suspended ceilings for the protection of the floors shall be treated differently from that provided for the protection of structural steel works in the ceiling space.

Where the space above a suspended ceiling is protected by an automatic sprinkler system it shall be exempted from the requirements for non-combustibility and surface spread of flame classification as specified in the above Table, provided the ceiling is not situated over an exit passageway, protected lobby or other required protected means of escape, and that the ceiling space is not used as an air plenum.

Explanations & Illustrations

Clause 3.3.6 : Fire rated board

Running of services in the space between the steel structure and fire-rated boards should be discouraged, unless it is unavoidable.

Services shall be limited to cables only and shall not include duct, gas pipes, fuel oil pipes, etc.

Explanations & Illustrations

In conjunction with Part 20, methods of test are provided for – Beams, columns, floors, flat roofs and walls (Part 21); Partitions, door sets and vertical shutter assemblies, ceiling membranes and glazed elements (Part 22); and Suspended ceilings protecting steel beams and  intumescent seals for use in conjunction with single acting latched timber fire-resisting door assemblies (Part 23).

Part 20 specifies standard heating conditions based on a temperature/time curve (Figure 3.4.1 - 2) which furnaces are required to follow; the temperature at defined locations close to the exposed face of the specimen under test rising to 821°C after 30 minutes and 1133°C after four hours.

The specimen to be tested should be either full size or, where the element exceeds the size that can be accommodated by the furnace, it must have the following minimum dimensions.

Non-separating elements: Vertical 3m high Horizontal 4m span

Separating elements: Vertical 3m high X 3m wide Horizontal 4m high X 3m wide

Specimens are normally heated to simulate their exposure in a fire, e.g. walls from one side, floors from beneath and columns from all sides.

Elements of building construction are required to satisfy various criteria according to their designed function in the event of fire. These are:

1. “Stability” or “Load-bearing capacity”: the ability of a load-bearing element to support its test load without excessive deflection.

2. “Integrity”: the ability of a separating element to resist collapse, the formation of holes, gaps or fissures through which flames and/or hot gases could pass, and the occurrence of sustained flaming on the unexposed face (the side of the specimen remote from the furnace).

3. “Insulation”: the ability of a separating element to resist an excessive rise in temperature on its unexposed face.

The criterion of “stability” or “load-bearing capacity” is applied only to load-bearing elements. For floors, flat roofs and beams, allowable vertical deflection is limited to 1⁄20 clear span.

Loss of “integrity” in the context of the formation of holes, gaps or fissures is judged by ignition of a cotton fibre pad. Where this test is not suitable, failure is deemed to have occurred if either a 25mm diameter gauge can penetrate into the furnace through a gap at any point, or a 6mm diameter gauge can penetrate into the furnace through an opening and can be moved for a distance of at least 150mm.

Loss of “insulation” occurs when the temperature on the unexposed face (the side of the specimen remote from the furnace) increases by more than 140°C (mean) or by more than 180°C at any point. Loss of “integrity” also constitutes loss of “insulation”.

Columns and beams have to satisfy only the criterion of “load-bearing capacity”; glazed elements are normally required to satisfy only “integrity”; and floors and walls have to satisfy all three criteria. It is pertinent to note that under Table 3.4A, doors are only required to satisfy “integrity”, leaving aside “insulation” as it is assumed unlikely that combustible materials would be stored against them. However, doors to protected lobbies, exit staircases and exit passageways should be provided with insulation against transmission of heat by radiation from the fire floor into the protected enclosures which occupants use for evacuation.

It is important to note that fire-rated glass door shall not be used in fire lift shaft, exit staircases and exit passageways. In other areas such as protected lobbies, separating and compartment walls, the use of fire-rated glass is permitted, provided the building is sprinkler-protected. See Cl.3.15.13 for more details.

Explanations & Illustrations

Cl.3.4.2b. provides the alternative to complying with the specification of tested prototype under BS 476 Part 20 to 23. Specification set out in Annex 3A to Cl.3.4 could be used and there is no need to obtain separate testing. However, on completion of the building works, the QP concerned is to forward to the RIs his/her certificate of supervision that the relevant specification listed in Annex 3A to Cl.3.4 had been complied with on site when applying for TFP or FSC.

Explanations & Illustrations

Clause 3.5.1 : Requirements of external walls

Where the external wall of a building which exceeds 15m in building height or is within 1m of the relevant boundary, the entire external wall shall be constructed wholly of non-combustible materials, apart from any external combustible cladding under  Cl.3.5.4 or internal combustible lining under Cl.3.13.4.

The external wall of building which is sited less than 1m from the relevant boundary, shall be imperforate, free of any unprotected area and have the necessary fire resistance rating, both inside and outside. The required fire resistance shall be achieved by the non-combustible part alone.

The external wall shall have the necessary fire resistance rating as required of the elements of structure of the building or compartment, in which the wall is located, in accordance with Table 3.3A, Part 1.

Any part of the external wall which is to be treated as unprotected area in accordance with Tables to Part II of Annex 3B to Cl.3.5, need not have fire resistance.

If the entire external wall is to be treated as unprotected area, the separation distance between the external wall and the relevant boundary shall comply with Tables to Part II of Annex 3B to Cl.3.5.

External walls, which are more than 1m from the boundary, need to resist the effect of fire from the inside only.

In cases where the external walls of buildings are situated less than 1m from relevant boundary, the external walls shall be treated as separating walls. The requirements under Cl.3.6 shall be fully complied with.

Clause 3.5.1b. : Requirements of external walls

Any beam or column forming part of an external wall and any structure carrying an external wall shall be constructed of non-combustible materials and have the necessary fire resistance rating of elements of structure, apart from any external cladding which complies with Cl.3.5.4 or any internal lining which complies with Cl.3.13.4. The required fire resistance shall be achieved by the non-combustible part alone.

Explanations & Illustrations

Part of a PG II building (not exceeding 3 storeys – building B in Figure 3.5.2a.(1) - 2, separated from the other parts (building A) by vertical compartment wall. Exemption would also apply to the building in Figure 3.5.2a.(1) - 1 which shall not exceed 3 storeys in height and be situated 1m or more from the relevant boundary.

Explanations & Illustrations

Single storey health care occupancy, schools, old folk’s home, etc. (PG III) need not comply with non-combustibility of external wall, if it complies with the requirements under Cl.3.5.2a.(2).

Explanations & Illustrations

Cl.3.5.2a.(3) is applicable to separated part of building as described in Cl.3.3.4b., which is illustrated in Figure 3.5.2a.(3) - 2.

Part A of the building comprising shops which is separated from other parts of the same building by a continuous vertical compartment wall would qualify for exemption of non-combustibility of external construction if:

1. the entire external wall does not exceed 7.5m in height, measured from the outside ground; and

2. the external wall is situated 1m or more from the relevant boundary.

Explanations & Illustrations

Unprotected areas in relation to a side or external wall of a building means:

1. a window, door or other opening, and

2. any part of the external wall which has less than the relevant fire resistance required in Cl.3.5, and

3. any part of the external wall which has combustible material more than 1mm thick attached or applied to its external face whether for cladding or any other purpose

The extent of unprotected areas in the external wall in relation to the setback from relevant boundary or lot boundary shall be in accordance with Annex 3B to Cl.3.5. The further the building is setback from the relevant boundary, the greater the amount of unprotected areas would be permitted.

An example on calculations of unprotected openings/setback from relevant boundary is given in page 56. The intensity of the heat produced by a fire within a building which can reach the relevant boundary will depend upon the extent of the “unprotected areas” in the external walls and the distance between these walls and the relevant boundary. The heat flux at the relevant boundary shall be less than that normally required for pilot ignition of combustible material after a period of exposure.

In situations where the extent of unprotected areas in external walls do not comply with Annex 3B, the QP has 4 alternatives. These are:

1. reduce the total unprotected area, or

2. increase the distance from the relevant boundary, or

3. introduce compartmentation within the building to break up the size of enclosing rectangle, or

4. introduce automatic sprinkler system so that the unprotected areas can be doubled or the distance from the relevant boundary can be reduced by half.

Explanations & Illustrations

Clause 3.5.3c. : Unprotected areas in any side of a building

The above clause is to provide an alternative for buildings protected with sprinkler system. QP/Building owner shall decide which option, Cl.3.5.3b. or  c. i.e. either double the unprotected openings or half the separation distance between the building and the relevant boundary, whichever is relevant to the building.

Clause 3.5.3d. : Unprotected areas in any side of a building

The above clause treats car park building differently by allowing the floor having the largest extent of unprotected openings to be used for the purpose of complying with Table 1 of  Annex 3B. This clause grants special relaxation in relation to its distance from the lot boundary for the purpose of complying with Table 1 of  Annex 3B.

In the above figure, the enclosing rectangle would apply to 1st storey elevation facing the relevant boundary, instead of the whole building, which forms one compartment.

The above clause treats car park building differently by allowing the floor having the largest extent of unprotected openings to be used for the purpose of complying with Table 1 of  Annex 3B. This clause grants special relaxation in relation to its distance from the lot boundary for the purpose of complying with Table 1 of  Annex 3B.

In the above figure, the enclosing rectangle would apply to 1st storey elevation facing the relevant boundary, instead of the whole building, which forms one compartment.

Explanations & Illustrations

1. It is necessary to assume a notional boundary when two or more detached buildings are erected on land in common occupation.

2. The notional boundary is taken to exist in space between the buildings and is positioned so that the external walls of building A and B facing the notional boundary comply with the separation distance requirement in accordance with Tables of  Annex 3B, based on the percentage of unprotected area and the purpose group of the compartment/floor.

3. Unprotected openings shall be assessed for each building separately. The separation distance between the two buildings shall be not less than the sum of the distance each building would require to a relevant boundary i.e. “a” is equal to or greater than the separation distance to the boundary for building A and “b” is equal to or greater than the separation distance to the relevant boundary for building B.

4. The notional boundary can be shifted next to external wall of building A or B, if the external wall has no unprotected areas and is constructed of non-combustible materials having the requisite period of fire resistance rating as the elements of structure of the storey compartment.

Explanations & Illustrations

Clause 3.5.7a.(1) : Vertical fire spread

The entire roof projection over the lower part of the building if less than 5m, then the entire roof projection shall be fire-rated with minimum 1-hr fire resistance rating. A fire occurring in the 3rd storey would spread vertically to 4th storey via the roof and windows. To prevent the fire spread vertically, the roof of 3rd storey should be fire-rated for minimum. 1 hour for a distance of 5m measured horizontally from the external wall of 4th storey abutting the roof of 3rd storey. The above requirement to fire rate the roof of 3rd storey will not be applicable if the building or lower part of the building is sprinkler-protected.

Clause 3.5.7a.(2) : Vertical fire spread

Providing fire rated wall with unprotected opening is an alternative to fire rating the roof under Cl.3.5.7a..

The above 2 figures show the 2 ways of preventing fire spread vertically from the lower floor to the upper floors.

Explanations & Illustrations

Clause 3.6.1a.(1) : Requirements of separating walls

Separating wall is the common wall that separates one house from another, as in the case of semi-detached or terraced houses. It is to prevent the spread of fire from house to house. The separating wall shall have the appropriate fire resistance rating as the elements of structure of the adjoining house having the larger floor area or cubical extent as the case may be. It shall not include fire-resisting glass.

Door opening in the separating wall is to provide communication between 2 houses is not acceptable, unless the 2 houses are under single ownership and occupied by a single family. Owner is required to furnish an undertaking to the SCDF that should one of the houses is to be sold, the door opening in the separating wall shall be bricked-up to have the necessary fire resistance as the adjoining wall.

Explanations & Illustrations

Clause 3.6.1b. : Requirements of separating walls

Walls between car porches (annotated by dash line) need not be separating walls provided the car porches are set back (annotated as ‘x’ above) adequately from their respective unit side boundaries.

Walls between car porches need to be separating walls (annotated by dash line) if the canopies span across the car porches and unit side boundaries.

Boundary no. 1 need not be a separating wall if the extended canopy can comply with set back to the unit side boundary as reflected above. Conversely, boundary nos. 2 & 3 need to have separating walls since the extended canopies cannot comply with set back from their respective side boundaries.

Explanations & Illustrations

Clause 3.6.2b. : Openings in separating walls

Doors are provided in separating walls to connect 2 buildings for public circulation. Prior approval shall be obtained before building plans are submitted for approval. The above provision for the purpose of public circulation shall not be taken to qualify for the requirements for the provision of area of refuge.

Explanations & Illustrations

Clause 3.6.2 : Openings in separating walls

1. Opening in the separating wall shall comply with the following conditions:

   1. QPs shall obtain prior approval from the SCDF before submission of building plan.

   2. If the adjoining unit or building is under different ownership; written consent from the owner shall be obtained for submission to the SCDF.

   3. Owners are to submit a written undertaking to the SCDF that should the opening in the separating wall is no longer required, it shall be restored to its original imperforate state.

2. Cl.3.6.2b. is not applicable to PG VI & VIII buildings.

   Door opening between 2 industrial units is not acceptable, unless the units are owned by one owner and occupied by a single company. In such a case the door opening in the separating wall shall be used solely for providing communication between the units and shall not be taken as means of escape during fire emergency, unless otherwise allowed. The owner is to furnish an undertaking to the SCDF that should one of the units be sold, the door opening in the separating wall shall be bricked-up to have the necessary fire resistance as the adjoining wall.

Explanations & Illustrations

Separating wall is carried right up above the roof coverings to act as a barrier to prevent fire spread over the roof level. The above clause addresses the concern at the junction of separating walls with roofs and other elements of structure to prevent fire from spreading through cracks and gaps at such junctions.

Explanations & Illustrations

Combustible materials built into separating wall would weaken the fire resistance integrity of the wall. Separating wall must be constructed of wholly non-combustible materials, including the beam, column or other structure carrying the wall. Exception is allowed for internal linings under Cl.3.13. However, for building under conservation, it would be acceptable if the original method of construction of floor is required to be retained.

Explanations & Illustrations

The provision of compartment floor would apply to separate basement from upper storeys in the case where the building has 4 or more upper storeys or levels and a basement. Under such situation, Cl.3.2.5d. shall be complied with i.e. the compartmentation between basement and 1st storey shall not be penetrated by any openings or services even if:

1. such openings are provided with fire doors; and

2. the services are in protected shafts.

Compartment walls and floors are to be totally imperforate except for the following permitted openings:

1. doors

2. protected shafts

3. ventilation ducts

4. pipes

5. chutes e.g. refuse, linen

Compartment walls and floors are to be constructed wholly of non-combustible materials, including any beam or column which forms part of the wall or floor and any structure which it carries. The walls and floors shall be constructed to have the necessary fire resistance of min. 1 hour to comply with the requirements of Cl.3.3. See Cl.3.2.5 on the provision of compartment walls and floors to apartment/maisonette unit. Provision of fire resisting glass in compartment wall or floor separating residential units is not allowed.

Explanations & Illustrations

It is a common practice to provide ½-hr fire resistance entrance door to flat or maisonette from common space, e.g. lobby. The fundamental reasons are that entrance doors are subject to normal everyday usage and that it is generally accepted that no combustible materials would be placed behind the doors.

In other situation, the door within compartment wall shall have the same fire resistance as the compartment wall. This is applicable to trap doors in floors.

Compartment walls and floors are required to be totally imperforate except for the above mentioned openings to permit movement of people, air, services etc. in the building.

Other provisions in the code which allow fire door to have ½ the fire resistance rating of the adjoining compartment wall are:

1. doors to protecting structure under Cl.3.8.6;

2. exit doors opening into an internal and external exit passageway under Cl.2.3.2b.(3) and  Cl.2.3.2c.(2) respectively; and

3. exit doors opening into protected lobby under Cl.2.2.13b..

Doors to protected shafts are required to have ½ the period of the fire resistance rating of the protecting structure surrounding the opening. The main reasons for the above relaxation are:

1. Exit doors if required to have the same period of fire resistance rating as the surrounding wall would be quite heavy. Occupants escaping into the protected staircase would need to push hard to open the doors. Besides having to overcome the weight of the doors, additional force would be required to deal with the self-closing device fitted to the doors and in certain cases, the force imposed by the staircase pressurisation system. This would slow down the evacuation process;

2. A fire that breaks into the shaft at one level would need to break out again at another level. The aggregate rating of the 2 doors, each at different level, would be considered as acceptable.

3. Door openings in protecting structures would be limited in size, hence the potential source of weakness in the overall integrity of the shaft is limited.

In other situation, the door within compartment wall shall have the same fire resistance as the compartment wall. This is applicable to trap doors in floors.

Explanations & Illustrations

Clause 3.7.3a. : Openings

Clause 3.7.3b. : Openings

Explanations & Illustrations

Compartment wall is carried right up above the roof coverings to act as a barrier to prevent fire spread over the roof level. The above clause addresses the concern at the junction of compartment walls with roofs and other elements of structure to prevent fire spreading through cracks and gaps at such junctions.

Compartment wall shall be brought up to the underside of the roof coverings, including jack roof to complete the fire separation and to prevent fire spread from compartment to compartment. See also Cl.3.6.3 (separating wall – roof junction)

Explanations & Illustrations

Construction of compartment walls and floors is to be entirely of non-combustible material, except for compartment walls or floors in buildings which are required to be retained by URA under the conservation programme. The exemption was an understanding between the SCDF and URA. As a general guide, QPs are required to seek prior consultation with the SCDF before making BP submission. There are also certain other exceptions:

1. floor finishes

2. wall or ceiling linings complying with Cl.3.13

3. suspended ceilings under Cl.3.3.6

Any structural members carrying compartment walls or floors must also comply with the requirement of non-combustibility. Apart from the contribution made by suspended ceilings under Cl.3.3.6, the fire resistance of the structural members must be attained without assistance from any combustible material (with the exception of buildings designated for conservation).

Explanations & Illustrations

Clause 3.7.7a. : Use of fire shutter

The employment of fire shutter to substitute compartment wall is now permitted provided the fire shutter in-lieu of compartment wall meet stability, integrity and insulation provisions when tested to BS 476: Part 20-23. Do note that placement of combustible items around fire-rated shutter is not allowed.

Clause 3.7.7b. : Use of fire shutter

The fire shutters, which are installed at the edge of atrium, void facing escalator and at door way are intended as relaxation. The reason for not requiring insulated fire shutter at door way is because the opening width is basically not overly big. The conventional fire door need not be tested to conform to insulation criterion. Hence, vertical fire shutter to substitute fire door will not be required to subject to insulation provision. All habitable spaces enclosed by the fire shutter are to be provided with exit for the occupants to escape either via a side door or a wicket door.

Explanations & Illustrations

The purposes of providing protected shaft are to delay or prevent the spread of fire between compartments through which staircases or other shafts pass directly and to enable people or things or air to pass between compartments. The purpose of each shaft are as follows:

1. The staircase shaft is a vertical shaft which enables the passage of
   movements of people.

2. The service shaft enables the passage of cable, building service ducts/pipes.

3. The lift shaft enables the movements of lift cars.

“Protected Shafts” include staircase, lift shafts, chutes, ducts or any other shaft enabling movement of people, goods, air, pipes, etc..

Protecting structures shall be treated as elements of structure for the purpose of determining the period of fire resistance rating.

Construction of compartment walls and floors shall be constructed entirely of non-combustible material. However, there were exceptions specially allowed for under the conservation programme. The exemption was an understanding between the SCDF and URA. As a general guide, QPs are required to seek prior consultation with the SCDF before making formal building plan submission.

Any structural members carrying compartment walls or floors must also comply with the requirement of non-combustibility. Apart from the contribution made by suspended ceilings under Cl.3.3.5, the fire resistance of the structural members must be attained without assistance from any combustible material (with the exception of buildings designated for conservation).

Explanations & Illustrations

Protected shafts penetrate across compartments or floors in a building. They can be shafts carrying utilities (piping, electrical and telecommunication cables etc.) or service shafts carrying lifts and exit staircases. The enclosing walls and floors to the protected shaft shall be constructed of non-combustible materials, including any beam or column, which forms part of the enclosure.

In the above figure, a protected shaft is enclosed at the top by roof slab, the sides by fire-rated walls and the bottom by the ground floor slab. The protecting structures to the shaft would exclude the roof slab, which is exposed to the external, the ground floor slab, which is in contact with the ground and any compartment wall, which separates one compartment from another.

Protected shaft is enclosed by internal walls, ceiling and floor. Protecting structures will include the walls and slab above; and the floor at the base of shaft is excluded, because it is a compartment floor.

Protected shaft is located against an external wall. The protecting structures will include internal walls, which are not compartment or separating wall.

Where the protection afforded to a compartment is penetrated to allow the movement of people, goods or anything else between compartments by means of e.g. a staircase, lift or duct, the protection to the compartment must not be lowered or diminished. This is achieved by enclosing the means of transportation from one compartment to another in a protected shaft which is so constructed that any penetration of the enclosures to the shaft poses no direct or indirect threat to the compartments connected by the shaft. Hence, the term “protected shaft” and “protecting structure” for the structure enclosing such a shaft. The elements enclosing the shaft (unless formed by adjacent external walls) are compartment walls and floors.

The above figure illustrates a shaft, which is enclosed by compartment or separating wall, external wall and internal walls called protecting structure. The fire resistance of the compartment or separating wall should be based on the size of the floor area or cubical extent of the adjoining larger compartment and shall not be less than 1 hour.

The fire resistance of the external wall would be determined by the separation distance requirements under Cl.3.5. The external wall is not a protecting structure and could be fully unprotected areas having no fire resistance. The remaining 2 walls of the shaft are protecting structure which must be imperforate except for certain permitted openings, e.g. inspection doors which need to have fire resistance equivalent to half that of the protecting structure. All protecting structure shall be constructed of non-combustible material except for surface linings, which shall comply with Cl.3.13. The fire resistance of the protecting structures shall be that for the elements of structure of the building.

Protecting structures exclude external wall. External walls need not have fire resistance rating, subject to complying with Cl.3.5 to be unprotected areas.

Explanations & Illustrations

Clause 3.8.3a.(1) : Openings in protected shaft

Protected shaft bounded on three sides by protecting structure and fourth side by an external wall. Permitted opening to each unit shall be protected by a door of at least one half of the fire resistance rating of the enclosing wall, or half an hour, whichever is the greater. The aggregate fire resistance of the 2 doors shall not be less than the fire resistance of the protecting structure.

Explanations & Illustrations

Clause 3.8.3a.(3) : Openings in protected shaft

Fire resisting doors to comply with Cl.3.9.2 and shall have ½-hr fire resistance or half the resistance of the enclosing walls, whichever is the greater:

1. Any opening in compartment floor/wall would constitute a break in compartmentation. Therefore even small service pipes, strictly speaking must be enclosed in protected shaft.

2. However, Cl.3.9 allows pipe size not greater than those sizes provided in Table 3.9A to be unprotected, provided the pipes are to be spaced at min. 50mm apart or half the diameter of the larger pipe, whichever is larger. This is to avoid clustering of pipes which would weaken the compartment floor or wall

3. Openings in compartment floors to accommodate staircases, lifts and services form a vertical shaft which can become a ready means of passage of fire from one storey to another, accentuated by the flue effect created by a fire.

4. Hence, protected shafts are needed to maintain the overall fire integrity of the building. However, these shafts need to have door openings for movement of people, e.g. staircase,  lifts and maintenance purposes in the case of shafts containing services. All the door openings to protected shaft are considered the sources of weakness in the integrity of the shafts and they must be protected.

5. Door openings

   Doors in protected shaft must have at least ½-hr fire resistance rating or half the fire resistance of the protecting structure whichever is greater.

   Such a relaxation from the full standard of fire integrity is reasonable as it is expected that combustible materials would not be placed next to the door and that a fire has to break into the shaft and break out again at the upper level. Also if the top of the shaft is adequately ventilated, the tendency for lateral spread is considerably reduced.

6. The primary purpose of protecting structure is to provide the compartmentation between floors. As such the structure shall have full fire resistance as the elements of structure. The relaxation on fire resistance accorded to fire doors shall not be extended to the protecting structure i.e. halve the fire resistance of the elements of structure. The main reason is that by halving the fire resistance of protecting structure, the threat of failure and collapse of the enclosing walls would be greater in times of fire emergency and should the walls collapse, large opening would be created in the shaft to permit the spread of fire and smoke, which is not acceptable. As to door openings in protected shaft, the eventual failure of the fire door is considered acceptable owing to the limited door opening size. See illustrations (c) and (d) [Figure 3.8.3a.(3) - 3].

7. Ventilation ducts

   Ventilation ducts are usually constructed of sheet metal, which do not have fire resistance and therefore should a fire occur, they will quickly distort and collapse leaving a hole in any wall through which they pass. Conversely, a fire occurring in the duct could also cause collapse.

   Therefore, where the duct penetrates the protected shaft, a fire damper should be fitted at the opening of the protecting structure. The fire damper shall be capable of sealing the opening in the protecting structure and be installed independently of the duct trunking. In this way, the fire damper would not be affected by collapse of duct work and be able to maintain the fire integrity of the shaft. See illustration (a) [Figure 3.8.3a.(3) - 1].

8. Pipes

   Where pipes are contained within a protected shaft, the problem of maintaining the integrity of the fire compartment is made simple, irrespective whether the pipes are made of UPVC or combustible materials. However, for gas pipes or pipes containing combustible liquids, they shall be located in separate shafts.

9. The construction of gas pipes shaft is different from other shafts owing to the need to provide through or external ventilation. Gas pipe shaft shall comply fully with SS CP 51. See illustration (b) [Figure 3.8.3a.(3) - 2].

10. General

    In order to maintain the level of integrity of protected shafts, openings in protected shafts shall be restricted to the following:

    1. Openings for pipe

    2. Door openings to lift shaft, staircase

    3. Openings for ventilation ducts

    4. Access openings for electrical cables shaft

    5. Openings for chutes, linen or refuse

Explanations & Illustrations

The requirement that all protecting structure shall be constructed of non-combustible materials is also spelled out under Cl.3.8.2. As to the provision of combustible finishes to floor, wall and ceiling, it must be observed that such provision will not be permitted inside protected shafts that are used for the passage of people such as exit staircases and exit passageways under Cl.3.10.4 and Cl.3.13.6.

Explanations & Illustrations

Protected shaft used for passage of people, such as exit staircases shall be provided with adequate natural ventilation by fixed openings in the external walls. Such openings shall have an area of not less than 10 percent of the floor area per floor of the staircase. Alternatively, the staircase can be mechanically ventilated under Cl.2.3.3d.(7). However, for internal exit staircase serving more than 4 storeys, the supply air shall be mechanically conveyed via a vertical duct extending through the staircase height and discharging from outlets distributed at alternate floor. Where the internal exit staircase exceeds 24m in height without provision for natural ventilation, the staircase shall be pressurised in accordance with Cl.2.3.3d.(8).

The mechanical ventilation system to internal staircase serving more than 4 storey and the pressurisation system to internal exit staircase exceeding 24m shall be connected to emergency power supply. In addition, a remote manual start-stop switch shall be make available to firefighters at the fire command centre, or at the fire indicating board where there is no FCC. The start-stop switch provides the firefighter a quick means to shut-off the fans should it be detected that smoke had been drawn into the staircase by the fresh air supply fan.

A protected shaft conveying piped flammable gas should be adequately ventilated directly to the outside air by ventilation openings at high and low level in the shaft or comply with the modes of ventilation allowed in SS 608. All gas pipe installations shall be vetted and approved by acceptable organisation (e.g. Powergas) before any works can be carried out on site.

Explanations & Illustrations

As the doors in the electrical and pipe shafts are opening into an external corridor which is naturally ventilated, there is no need to fire rate the doors.

Protected shaft A serves 2 compartments. Compartment A could be a common area e.g. lounge and compartment B in factory/warehouse unit.

Door A1 is opening in the direction of exit travel, whereas door A2 is the entrance door of the factory/warehouse unit, which swings inward. The number of exit door openings in a protected shaft containing an exit staircase shall not exceed two per floor. This is to prevent additional openings from weakening the integrity of the protecting structure.

The aggregate fire resistance of door A1 and A2 shall not be less than the compartment wall or the protecting structures to the shaft. This is to ensure that the fire resistance between compartment A and B is not reduced at the door openings.

Door A1 can be held in the open position provided it is fitted with electromagnetic or electromechanical device. See Cl.1.4.34.

All doors in shaft A & B shall have the fire resistance rating of half that of the enclosing protecting structures to the shafts, but shall never be less than half hour. See also Cl.3.8.3 for further explanation.

Protected shaft A serves 2 compartments. Compartment A could be a common area e.g. lounge and compartment B in an office unit.

All doors in shaft A & B shall have the fire resistance rating of half that of the enclosing protecting structures to the shafts, but shall never be less than half hour. See also Cl.3.8.3 for further explanation.

Door A1 is opening in the direction of exit travel, whereas door A2 is the entrance door of the health care occupancy unit, which swings inward. The number of exit door openings in a protected shaft containing an exit staircase shall not exceed two per floor. This is to prevent additional openings from weakening the integrity of the protecting structure.

The aggregate fire resistance of door A1 and A2 shall not be less than that of the compartment wall or the protecting structures to the shaft. This is to ensure that the fire resistance between compartment A and B is not reduced at the door openings.

Door A1 can be held in the open position provided it is fitted with electromagnetic or electromechanical device. See Cl.1.4.34.

Explanations & Illustrations

Clause 3.8.7a. : Protected shaft containing exit staircase

A fire lift and fire lift lobby in a building, which exceeds 24m in habitable height, have to be complemented by an exit staircase adjacent to them. Separate ventilation shafts are required to be provided for the staircase and fire lift lobby as depicted in Cl.7.1.10.

Exit staircases serving any building irrespective of the height, shall be devoid of combustible wall, floor and ceiling finishes. Building services which are not solely serving the exit staircase shall not be allowed to be routed through or inside the staircase. This is to prevent any possibilities of a fire occurring inside the staircase and the spread of fire into the staircase via the services such as electrical cables, ducts, combustible pipes, etc.. Cl.6.2.2 of the Fire Code allows vertical stack of rising main and landing valve to be located inside the staircase as a last resort where smoke-stop lobby and common area outside the staircase are not available. SS CP 10 allows sub-alarm panels to be located in the exit staircase provided there is no fire lift lobby or smoke-stop lobby in the building. The fire alarm cables shall be in metal conduit or trunking. This relaxation shall not apply to buildings which are more than 4 storeys in height where provision of smoke-stop lobby is a requirement.

The exit staircases are the means of escape in fire emergencies. All occupants must use the staircases to evacuate safely from any storey level to the final exits at ground level. The time taken to descend a staircase in a high-rise buildings could be more than an hour. With the staircase fully packed with evacuating occupants during an emergency, the staircase must be maintained safe from smoke, heat and fire throughout the fire resistance period of the enclosing protecting structures to the staircase. An exception is allowed under Cl.3.8.9d. for maximum 4 storey residential building.

Explanations & Illustrations

Clause 3.8.7b. : Protected shaft containing exit staircase

Building designed with single exit staircase shall have the protecting structure constructed of masonry, which is more solid and stable than fire-rated dry walls. The main concern is that if the protecting structure, which is constructed of dry wall is damaged, smoke and heat would get into the staircase to affect the evacuees making their way down. Single exit staircase shall have its protected structure constructed of masonry.

Where two independent staircases are provided, the protecting structure to each of the staircase can be constructed of drywall.

Where a building is designed with a pair of scissors staircases to meet the provision of exit requirements, the scissors staircases shall be considered as within a common shaft if drywall is used for the construction of the protecting structure. The main reason is that if one of the shaft is damaged, the other shaft is likely to be affected, thereby causing smoke to get into both staircases. This would render the pair of scissors staircases inaccessible. In addition, the drywall enclosures are prone to other damages, thus affecting the effectiveness and integrity of the protected shafts. However, for the purpose of exit computation, the pair of scissors staircases shall literally be taken as 2 staircases though it could only qualify as a single shaft.

Non-combustible steel studs, insulation materials and fire-rated boards shall be used for the construction of drywall.

Explanations & Illustrations

Clause 3.8.8a. : Lift shaft

Lift shaft which is not located at the edge of atrium floors or at the external wall outside the building shall be constructed of masonry.

Cl.3.8.8a. specifically permits combustible liquid in the mechanism of hydraulic lift. The liquid is concealed in vessels and forms part of the mechanical system to permit the homing of the lift during an emergency. The liquid has a high flash point of over 400°C.

Lift shaft, which is not located at the edge of atrium floors or at the external wall outside the building, shall be constructed of masonry.

Cl.3.8.8a. specifically permits combustible liquid in the mechanism of hydraulic lift. The liquid is concealed in vessels and forms part of the mechanical system to permit the homing of the lift during an emergency. The liquid has a high flash point of over 400°C.

Explanations & Illustrations

Clause 3.8.8c. : Lift shaft

In the above figure the lift is unenclosed and being located within the atrium void. There is no penetration of any compartment floor and smoke migration caused by the ‘piston-effect’ of lift movement is no longer a concern. Smoke from a fire in any occupancy floor will flow from the ceiling layer into the atrium void where it will tend to rise upwards due to its natural buoyancy. A smoke control system would eventually extract the smoke out of the building.

The lift is sited outside the external wall of the building. There is no concern of smoke and heat being transferred from floor to floor. Hence it is not required to be enclosed in a protected shaft. This type of lift is commonly known as ‘bubble lift’ or ‘sky lift’.

The above figure shows that the lift is located away from the atrium void. As the lift punctures through the compartment floors, it must be enclosed in a protected shaft to prevent the spread of smoke and heat from floor to floor.

Explanations & Illustrations

Clause 3.8.8d. : Lift shaft

All lift shafts shall be vented at the top in accordance with SS 550. In situations, where the lift shafts could not be brought above the roof as shown in Figure 3.8.8d. – 2, horizontal fire rated duct could be used to provide air relief to the lift shaft. If the duct is not fire rated, appropriate fire damper could be provided in the wall of the protected lift shaft as shown ‘A’ in the above diagram. The above relaxation shall not be applicable to fire lift.

Explanations & Illustrations

Clause 3.8.8f. : Lift shaft

Floor indicator panel should be surface mounted. If it is built into the transom panel, care should be taken to ensure that the fire resistance of the panel is not lowered. It is a common mistake to puncture the transom panel to receive the floor indicator panel without giving consideration to the fire integrity of the panel. Such practice contravenes the above requirement, as Cl.3.8.2 requires that the protecting structure, including the transom panel, forms a complete barrier and should have the appropriate fire resistance rating.

Explanations & Illustrations

Clause 3.8.8g. : Lift shaft

Lift opening into basement and not adjoining a void that opens to the sky or any external spaces, shall be provided within a smoke-stop lobby having 1-hr fire-rated enclosures and ½-hr fire door.

The smoke-stop lobby acts as a buffer zone to prevent smoke from being drawn into the lift shaft through the ‘piston-effect’ of the movement of the lift.

Lift opening into basement storey and adjoining a void opening to the sky or any external spaces does not require a smoke-stop lobby. Smoke occurring in the vicinity of the lift would be drawn into the void and vented upward into the open space. This provision would help to reduce the chance of smoke being sucked into the lift shaft.

Explanations & Illustrations

Clause 3.8.8h. : Lift shaft

Explanations & Illustrations

Clause 3.8.9a. : Protected shaft containing other services/installations

The protecting structure for protected shaft containing kitchen exhaust duct and mechanical ventilation ducts which pass through one or more floors and serving areas such as:

1. Exit staircases and exit passageways

2. Smoke-stop and fire lift lobby

3. Areas of refuge within the same building

4. Emergency generator

5. Engine driven fire pump

shall be constructed in masonry. Each shaft shall be separately compartmented from one another. Protected shaft containing ducts serving other areas not mentioned above and which pass through two or more floors can be constructed of fire-rated materials, instead of masonry.

Kitchen exhaust duct shall be in a separate compartment from that for a mechanical ventilation duct. Kitchen exhaust ducts serving different kitchens shall be in separate shafts. Mechanical ventilation duct serving the area of refuge shall be in different shaft from that serving the pump room. The main reason for separate shafts is to prevent smoke and fire spread from shaft to shaft.

1. In the above figure, the roof is not considered a floor slab, as it is exposed to the external air. Hence, the flue or duct does not pass through the floor. (See Kitchen 2)

2. When the flue or duct passes through one or more floors (any floor), it shall be encased in masonry material to ensure stability and prevent mechanical damage. (See Kitchen 1)

Kitchen exhaust shaft for each kitchen is completely separated. The horizontal run of the exhaust from kitchen 1 is protected with fire-rated material.

If a flue, or duct containing flues or appliance ventilation duct(s), passes through a compartment wall or compartment floor, or is built into a compartment wall, each wall of the flue or duct should have a fire resistance of at least half that of the wall or floor in order to prevent the by-passing of the compartmentation.

Explanations & Illustrations

Clause 3.8.9b. : Protected shaft containing other services/installations

Protected shaft containing electrical cables shall be interrupted at every floor with cavity barrier having min. ½-hr fire rating to prevent vertical spread of fire and smoke. The main concern is that cables are a source of fuel and ignition. The presence of fire stopping at every floor would help to confine fire to a single storey or segment of the shaft.

Protected shaft containing telecommunications cables including cable TV lines is provided with cavity barrier at vertical intervals not exceeding 15m or 3 storeys whichever is the shorter. The cables are mainly of low voltage and hence of a lower risk when compared to electrical cables.

Explanations & Illustrations

Clause 3.8.9c. : Protected shaft containing other services/installations

Provision of self-closing device for the inspection door of a protected shaft, which is interrupted by barriers having ½-hr fire resistance at every floor, is not required. The above relaxation is also applicable to telecommunication cable shafts, provided they are interrupted by  barriers with fire resistance of at least ½ hour at every floor level.

An important point to note is the depth of the shaft which shall not exceed 750mm. If it exceeds 750mm, the shaft would be considered as a room and provision of self-closing device for the fire door becomes a necessity. The above relaxation is based on the understanding that it is unlikely that a shaft would be converted to a store if  its depth is less than 750mm and that the door would normally be kept in the locked position when workmen are not carrying out servicing work. Also, maintaining the door in locked position is the responsibility of the management corporation of the estate.

Explanations & Illustrations

Clause 3.8.9d. : Protected shaft containing other services/installations

Protected shafts such as for lift, TAS/Elect/Water/Cables are permitted to be located within a protected shaft containing an exit staircase for buildings under PG II, provided:

1. that building does not exceed 4 storeys where provision of smoke-stop lobby is not a requirement; and

2. that no shaft shall contain pipes carrying gas or combustible liquids. The above exception is only applicable to low-rise buildings where provision of smoke-stop lobby is not a requirement and that the staircase would be naturally ventilated. However, where there is availability of common area, such services shall be located outside the staircase shaft, see Figure 3.8.9d. – 2.

A factory or warehouse building which does not require the provision of smoke-stop lobby to exit staircase by virtue of its height shall be required to comply fully with the above requirement. All protected shafts containing services are located in a common lobby adjoining the exit staircase.

Although the services are enclosed in protected shafts, they are not permitted to be located in exit staircase. The main reasons are:

1. Within the protected shaft, the combustible materials e.g. Cables PVC pipes are source of fire risk. A fire could originate from these combustible materials and spread into the exit staircase enclosure.

2. Exit staircase is a dedicated route for escape of occupants, services which are not serving the staircase shall not be located inside the enclosure.

Explanations & Illustrations

For functional purposes, openings in compartment walls, floor etc. are required in buildings to allow movement of people and the installation of services such as pipes, ventilation ducts etc.. To prevent the spread of fire and smoke, such openings shall be appropriately protected.

Explanations & Illustrations

Clause 3.9.2a. : Fire doors

The two 1-hr fire door arrangement is deemed to satisfy compartmention and be equivalent to the fire resistance rating of the compartment wall (2 hours).

The provision of fire doors shown in the above figure usually occur in separating walls, compartments e.g. hotel guestrooms or protecting structures / dormitories, hostel bedrooms or protecting structures. The 2 doors shall be independent of each other and having its own door frame. However, the 2 doors may share the same door frame only if that set of door is tested to achieve the required rating. This arrangement shall not form part of the escape exit route.

Explanations & Illustrations

Clause 3.9.2b. : Fire doors

All fire doors are required to be fitted with an automatic self-closing device which shall not include rising butt. Self-closing device is not required to be fitted to doors of protected shafts having a depth of not more than 750mm under Cl.3.8.9c..

Fire resisting door to exit openings of apartment/maisonette units, protected staircases, protected lobbies, exit passageway, compartment walls etc. shall have minimum half hour fire resistance. Doors to exit facilities shall not be fitted with any locking device. However, doors to exit openings of apartment/maisonette units would be fitted with locking devices for security reasons. As fire door is to protect the openings in exit facilities, it should always remain in the closed position to prevent the spread of smoke and heat. The main function of the self-closing device is to return the door to its closed position after being opened for movement of occupants, goods etc.. The passage latch fitted to the door is to hold the fire door in closed position to counteract the pressure differential between the door in a fire situation.

Many private residential apartment/maisonette buildings have card key access or automatic locking devices fitted to doors of exit staircases to prevent unauthorised access by outsiders. 

To gain entry into the staircase or to exit from it into any floor, the occupants need to key in a code number or use a card key access to unlock or release the locking device to the door. In times of power failure or activation of fire alarm system, if available, the locking device would be unlocked by itself and all the exit doors could be opened manually. Prior approval should be obtained from the SCDF before any door to exit facility is fitted with any form of locking device.

When the door to the exit facilities consists of double leaves or multiple leaves,  all the leaves shall be fitted with self-closing device and sequential closer.

Where the entrance door of the apartment or maisonette unit  consists of large and small leaves, self-closing device shall be required to be provided to the large leaf, provided the clear width of the opening of the large leaf when open at an angle of 90° is not less than 850mm. The smaller leaf is not to be taken into consideration as it would usually be bolted-shut, unless there is a need to open it for movement of large furniture, etc.. If the door opening has 2 leaves of equal width for use as exit to meet the minimum clear width of opening under Cl.2.2.9b., both leaves shall be fitted with self-closing device and sequential door closer. 

Self-closing device to fire door shall be properly maintained regularly. Faulty device shall be repaired immediately to prevent fire door being left in the open position.

Explanations & Illustrations

Clause 3.9.2f. : Fire doors

All fire doors are required to be listed under a recognised certification body. It is important to note that fire door opening into pressurised exit staircases shall not be fitted with electromagnetic or electromechanical device. This is to ensure that the integrity of the pressurised exit staircase is maintained at all times.

Explanations & Illustrations

Clause 3.9.3 : Pipes

The clustering of pipes without proper spacing would further weaken the integrity of the fire resisting walls in times of fire emergency.

External corridor would be well ventilated. Hence fire risk is lower and the threat of spread of fire and smoke from floor to floor is very much reduced.

Explanations & Illustrations

Clause 3.9.4a. : Ventilation ducts

Proper fire stopping around the duct where it penetrates the compartment floor/wall and provision of fire damper at the compartment wall/floor would help to prevent fire and smoke spread from compartment to compartment.

Clause 3.9.4b. : Ventilation ducts

The provision of fire damper at the entry to the protected shaft would help to complete the compartmentation to prevent fire or smoke from being drawn into the protected shaft via ventilation duct.

Explanations & Illustrations

Separate kitchen exhaust shaft enclosed in masonry or drywall construction shall be provided for Kitchen (1) and (2). This is to prevent fire and smoke from spreading from one compartment to another. The wall enclosing the shaft shall have the same fire resistance as the compartment wall or floor.

The enclosing walls to the duct serving the laboratory are required to be constructed of non-combustible materials, instead of masonry, and need to have not less than ½ the minimum period of fire resistance rating of the compartment walls or floor through which the duct passes.

Explanations & Illustrations

Services not forming part of the FCC, Fire Pump Room, Emergency Generator Room and Smoke Control Fans Rooms but routed inside the mentioned spaces are disallowed. In the case of site constraint, the services not required for the operation of the mentioned system shall be separated and  encased with masonry construction.

Explanations & Illustrations

Clause 3.9.7 : Services passing through FCC, fire pump room, emergency generator room & smoke control fans room

Where the services need to be routed inside fire lift lobby and smoke-stop lobby, adequate protection must strictly be adhered to. The unprotected services are required to be protected with 1-hr fire resistance enclosure, or separated with 1-hr fire resistance ceiling from the protected lobby space.

Explanations & Illustrations

The exit staircase shall be separated away from all unprotected spaces and openings. For more details of separation distance for unprotected openings, refer to Cl.2.3.3.

Explanations & Illustrations

The protecting structure, excluding the external wall, to the staircase shall be constructed of non-combustible materials. Ceiling/wall and floor finishes shall be of non-combustible materials to ensure that the level of safety in the staircase is maintained at all times. The only exception allowed is the handrail material.

Explanations & Illustrations

Concealed spaces or cavities in building provide a ready route or flue for smoke and flame to spread undetected for quite some time, thus increasing the risk to life safety of occupants in the building. This is particularly so in the case of void spaces above a suspended ceiling or in a roof space or in a raised floor system. Provisions are available in the Fire Code to reduce the risk of concealed smoke and flame spread by the introduction of cavity barrier when the area or linear dimensions of cavities exceed the limits as per Table 3.11A. Cavity barriers shall be constructed of non-combustible materials and shall have at least ½-hr fire resistance.

Explanations & Illustrations

“Cavity barrier” means any construction provided to close a cavity against, or restrict the spread of smoke and flame within it.

In Figure 3.11.2 - 1 above, cavity barriers are used to close the edges around the window opening. Similar application is provided to window in external cavity wall in Figure 3.11.2 - 2.

Explanations & Illustrations

Cavities must be closed where the fire barrier elements (compartment walls) abut the cavity (including the frame of a door).

Cavity in the walls shall be closed where the compartment floor abuts it.

Any cavity within an element, or at the junction of two elements, must be closed by a cavity barrier.

It is a common practice to bring the compartment wall right-up to the underside of the structural slab above. The cavity barrier above the compartment wall shall be treated as an extension of the compartment wall below.

The roof space over a protected staircase must be separated by either a cavity barrier at (a) having the same fire rating as the wall of the staircase below, or a fire-rated ceiling at (b). See Cl.1.4.18 for further illustration. Extending the masonry wall right up to the underside of the roof coverings at (a) would meet the requirement under Cl.3.10 of having masonry enclosure to exit staircase.

Explanations & Illustrations

Cavity barriers must be tightly fitted to rigid construction and mechanically fixed in position wherever possible. Where this is not possible (for example, in the case of a junction with slates tiles, corrugated sheeting or similar materials) the junction should be fire-stopped to prevent the spread of fire and smoke in the concealed space.

Cavity barriers must also be fixed so that performance will not be made ineffective by:

1. movement of the building due to subsidence, shrinkage or temperature change; 

2. collapse in fire of any services penetrating them;

3. failure in fire of fixings; and

4. failure in fire of any material or construction which they may abut. For example, if a suspended ceiling is continued over the top of a fire-resisting wall or partition, and direct connection is made between the ceiling and the cavity barrier above the line of the wall or partition, premature failure of the cavity barrier can occur when the ceiling collapses. However, this does not arise if the ceiling is designed to provide fire protection of 30 minutes or more.

failure in fire of any material or construction which they may abut. For example, if a suspended ceiling is continued over the top of a fire-resisting wall or partition, and direct connection is made between the ceiling and the cavity barrier above the line of the wall or partition, premature failure of the cavity barrier can occur when the ceiling collapses. However, this does not arise if the ceiling is designed to provide fire protection of 30 minutes or more.

The main purposes of extending the compartment walls into the ceiling space are to complete the compartmentation to each apartment unit and to prevent smoke and fire spread via the concealed ceiling space.

Compartment walls should be carried right up to the full storey height, to a compartment floor above or to the roof coverings, as appropriate. The walls in the ceiling above the common corridor shall not be treated as cavity barriers. They shall be treated as extension of the compartment walls below.

The main purposes of extending the compartment walls into the ceiling space are to complete the compartmentation to each apartment unit and to prevent smoke and fire spread via the concealed ceiling space.

Explanations & Illustrations

Penetrations of cavity barriers shall be restricted to those illustrated above. All openings through cavity barriers must be no larger than necessary and be fire stopped. The fire stopping shall not restrict thermal movement.

Explanations & Illustrations

The space between the floor and the raised floor or platform shall not be used for storage purpose. Electrical wiring in the space shall be in conduit in accordance with SS CP 5. Under Table 3.11A, cavity barrier is to be provided at 20m dimension in any direction. Sleeper walls, which are provided for support to the floor or platform, act as a cavity barrier in the concealed space.

The space between the floor and the raised floor or platform shall not be used for storage purpose. Electrical wiring in the concealed space shall be in conduit in accordance with SS CP 5. Under Table 3.11A, cavity barrier is to be provided at 8m dimension in any direction. As such, ½-hr fire-rated cavity barriers are provided to sectionalise the concealed space.

Explanations & Illustrations

Clause 3.11.8e. : Raised floors with or without accessible panels

Non-combustible raised floor panels and supports are allowed to be used in non-sprinkler or sprinkler-protected buildings.

Raised floor panel constructed of combustible core, e.g. chipboard, shall only be allowed to be used in buildings protected by sprinkler system and that the underside of the raised floor is adequately covered by the sprinkler system.

Explanations & Illustrations

Clause 3.11.8g. to j. : Raised floors with or without accessible panels

The provision of cavity barriers shall comply with Table 3.11A of the Fire Code.

Non-sprinkler protected building

Cavity barriers shall be provided in accordance with Table 3.11A. The height of concealed space (H), measured between the finished floor level and the underside of the raised floor decking shall not exceed 400mm. The concealed space shall be fitted with smoke detection system in accordance with SS CP 10 Code of Practice for the Installation and Servicing of Electrical fire Alarm Systems. SS CP 10 also allows that smoke detector system is not required to be provided in concealed space which does not exceed 150mm in height. Automatic smoke detection system is applicable if the height of concealed space exceeds 400mm.

Sprinkler protected building

Cavity barriers shall be provided in accordance with Table 3.11A. Where the height of the concealed space does not exceed 400mm, smoke detection system complying with SS CP 10 shall be provided. The height of concealed space may exceed 400mm if the space is fitted throughout with sprinkler system. Where sprinkler system is provided inside the concealed space, cavity barriers are not required to be provided – Cl.3.11.8j..

Explanations & Illustrations

Clause 3.11.9d. : Provision for concealed spaces between floor or roof & suspended ceilings

Provision of cavity barriers in concealed ceiling space may not required if the following requirements are complied with:

1. the space is not used for storage purpose; 

2. the supporting elements eg. ceiling hangers or supports are constructed of non-combustible material; 

3. the exposed surfaces within the concealed space is of Class 0 flame spread (excluding surfaces of any pipe, cable, conduit or insulation of any pipe or duct); and

4. concealed space does not exceed 800mm in depth; if exceeds 800mm, it shall be fitted with smoke or heat detectors.

Explanations & Illustrations

Clause 3.11.9e.(1) : Provision for concealed spaces between floor or roof & suspended ceilings

Provision of cavity barriers in the concealed ceiling space may not required if the following are complied with:

1. the space is not used for storage purpose;

2. the supporting elements eg. ceiling hangers or supports are constructed of non-combustible material;

3. the exposed surfaces within the concealed space is of Class 0 flame spread (excluding surfaces of any pipe, cable, conduit or insulation of any pipe or duct); and

4. concealed space does not exceed 400mm in depth.

Clause 3.11.9e.(2) : Provision for concealed spaces between floor or roof & suspended ceilings

Provision of cavity barriers in the concealed ceiling space may not required if the following are complied with:

1. the space is not used for storage purpose;

2. the supporting elements e.g. ceiling hangers or supports are constructed of non-combustible material;

3. the exposed surfaces within the concealed space is of Class 0 flame spread (excluding surfaces of any pipe, cable, conduit or insulation of any pipe or duct); and

4. no combustible material is used within the concealed space. However, where the combustible content is small in quantity, the SCDF may, at its discretion grants exemption, provided the space is protected by sprinklers installed on the extended basis under SS CP 52 (whole coverage to be extended to the ceiling).

Clause 3.11.9e.(3) : Provision for concealed spaces between floor or roof & suspended ceilings

Provision of cavity barriers in the concealed ceiling is not required. See also Cl.3.11.10 for further relaxation.

Explanations & Illustrations

Clause 3.11.9f. : Provision for concealed spaces between floor or roof & suspended ceilings

Provision of cavity barriers in the concealed ceiling space may not required if the following are complied with:

1. the space is not used for storage purpose;

2. the supporting elements e.g. ceiling hangers or supports are constructed of non-combustible material;

3. the exposed surfaces within the concealed space is of Class 0 flame spread (excluding surfaces of any pipe, cable, conduit or insulation of any pipe or duct); and

4. concealed space does not exceed 800mm in depth; if exceeds 800mm, it shall be fitted with smoke or heat detectors.

Explanations & Illustrations

1. Where the concealed ceiling space is protected by automatic sprinkler system, the above clause allows the following:

   1. Provision of cavity barrier is exempted;

   2. Combustible materials such as hardwood timber hangers for ceiling; and

   3. Exposed surfaces within the ceiling space may be of any class other than Class 0 flame spread ie. timber members.

2. The above relaxation shall not apply if the above ceiling construction is situated over an exit passageway or other designated means of escape facilities.

Explanations & Illustrations

The main concern is that spaces meant for safe escape of occupants shall be kept free of combustible materials. Common corridors are treated as escape routes. The exposed surfaces within ceiling space shall have a flame spread rating of Class ‘0’.

Explanations & Illustrations

Clause 3.12.1. : General provision

Fire stopping is concerned with ensuring that the fire-resisting capability of a component, i.e. separating wall, compartment wall/floor, cavity barrier is not diminished or impaired when penetrated by services for example, a pipe, ducts, etc..

Therefore whenever gaps are created by the penetration of such pipes, ducts in the fire-rated wall/floor, they must be kept as few as possible. The spacing and internal diameter of pipes passing through any elements of structure or cavity barrier shall comply with Cl.3.9.3 and Table 3.9A.

Explanations & Illustrations

Clause 3.12.3 : Materials for fire stopping

To prevent displacement, materials used for fire stopping should be reinforced with (or supported by) materials of limited combustibility in the following circumstances:

1. in all cases where the unsupported span is greater than 100mm, and

2. in any other cases where non-rigid materials are used (unless they have been shown to be satisfactory by test)

Preference should be given to proprietary fire stopping and sealing system.

When cement mortar or gypsum board plaster or cement or gypsum based vermiculite/perlite mixes is used as fire stopping material, care should be exercised to ensure that workmen properly fill up the entire gaps with the appropriate fire stopping material instead of carrying cosmetic application by just filling up the gaps superficially.

Explanations & Illustrations

BS 476: Part 6 refers to a standard fire test for propagation of products.

Under this test, there is a means of comparing the contribution of combustible building materials to the growth of a fire by providing a measure of the rate of heat evolution of the samples, exposed in a small combustion chamber.

The performance of each sample is expressed as a numerical index from 0 to 100 or more. Low values of the indexes indicate a low rate of heat release. Three to five specimens are tested.

Index of performance I = i1 + i2 + i3 where sub-index i1 is derived from the first three minutes of test, i2 from the following seven minutes, and i3 from the final ten minutes. A high index i1 indicates an initial rapid ignition and heat release.

Explanations & Illustrations

BS 476: Part 7 refers to a standard fire test for the classification of the surface spread of flame of products. This test is able to determine the tendency of surfaces of flat material to support the spread of flame across their surfaces and specifies a method of classification appropriate to wall and ceiling linings. Class 0 represents the best performance, followed in descending order by Class 1, Class 2, Class 3 and Class 4. This clause is rephrased for clarity.

Explanations & Illustrations

The reason for having Class 0 is that Class 1 covered too wide a range of performance for use in critical areas. Where a higher degree of protection is required, for example in exit staircases, exit passageways (which constitute the escape route), Class 0 is specified.

Explanations & Illustrations

Clause 3.13.4c. : Class of flame spread to be not lower than specified

In the design of the auditorium, there is a need to meet the acoustic requirements. Timber was then considered as a preferred material for use. The above clause provides the relaxation for the use of timber as wall linings, provided the aggregate area of the timber linings does not exceed 50% of the whole surface area of the side walls of the auditorium. The other reason for the above relaxation is that each auditorium is required to be constructed as a fire compartment.

Clause 3.13.4 : Class of flame spread to be not lower than specified

Wall, ceiling and floor finishes to exit staircase (including exit passageway) shall be of non-combustible materials or Class 0 (sprinkler-protected). For rooms, the extent of wall and ceiling finishes shall comply to Cl.3.13.5a. and  b. respectively.

Where a building is protected by automatic sprinkler system, the surfaces of the walls and ceilings of the circulation space (corridor) and institutional occupancy area can be downgraded by 2 classes subject to Class 3 being the lowest.

Explanations & Illustrations

Clause 3.13.5a.(1) : Where class of flame spread can be of any class not lower than Class 3

The linings to internal surfaces of a wall in a room or compartment are permitted to have any Class as permitted under Table 3.13A.

Clause 3.13.5a.(2) : Where class of flame spread can be of any class not lower than Class 3

Computation of 60m² will be based on total surface areas of walls in a room having not lower than Class 3. In the above diagram, the total surface area of the 4 walls, if finished with Class 3 materials shall not exceed 60m².

In the above diagram there are two compartments. Each compartment can have a total of 60m² of combustible wall finishes of not lower than Class 3. Subsequently, if the compartment wall is removed, there is a need to review the provision of wall finishes, subject to the total wall finishes to the whole floor shall not exceed 60m². Area of wall finishes in excess of 60m² is required to be removed.

In the above diagram, if subsequently the compartment wall as shown in dotted lines is removed, the overall 60m² shall be based on total floor area of compartment A.

In situation where multiple floors are interconnected to form one compartment by atrium design, waiver application is required to vary the max. 60sq.m

For Class 3 wall finishes, the total area of 60sq.m excludes :

1. door frames and unglazed parts of doors;

2. window frames and frames in which glazing is fitted;

3. architraves cover moulds, picture rails, skirtings and similar narrow members; and

4. fitted furniture.

Explanations & Illustrations

Clause 3.13.5b.(1) : Where class of flame spread can be of any class not lower than Class 3

Ceilings of living room, dining room, kitchen and bedrooms are permitted to have combustible finishes of class not lower than Class 3. The control is based on the size and spacing of the ceiling material.

The above clause is intended for lighting diffuser Any part of a ceiling to circulation space e.g. corridor can have not lower than Class 3 flame spread, provided each part shall not exceed 2.5m² and is separated from other such part by minimum 3.5m.

Explanations & Illustrations

Clause 3.13.5b.(2) : Where class of flame spread can be of any class not lower than Class 3

1. Factories and warehouses are usually provided with translucent roof sheets or sky light for natural lighting.

2. Any part of ceiling which is combustible shall have an area not exceeding 5m² and a class not lower than Class 3 flame spread. It shall be separated from any such part by at least 1.8m.

3. The aggregate area of such part of ceiling shall not exceed 20% of the floor area.

Explanations & Illustrations

Clause 3.13.5b.(3) : Where class of flame spread can be of any class not lower than Class 3

Unenclosed loading/unloading platform

Covered linkway connecting 2 buildings

In-addition to the above, ceilings to balcony, verandah, open carport are also allowed to have not lower than Class 3 flame spread. The above relaxation is allowed as the ceilings are located at the periphery of the building where smoke and heat could easily be dispersed into the exterior air.

Any material, including gypsum board or plaster board, which satisfies the requirements under Cl.1.4.71 as non-combustible material is to be treated as acceptable under the above clause, regardless of the presence of the 0.5mm thick paper facing.

Explanations & Illustrations

Clause 3.13.5b.(4) : Where class of flame spread can be of any class not lower than Class 3

Finishes to ceilings in circulation space in the building shall have a surface flame spread rating of not lower than Class 0 as required for under Table 3.13A.

Finishes to ceiling of a room or compartment are permitted to have any class as permitted under Table 3.13A.

A garage or outbuilding can have ceiling not lower than Class 3 flame spread, provided the accessible floor area does not exceed 40m².

Explanation

The above clause grants relaxation on the control of wall and ceiling finishes which are not more than 1.0mm thick mounted on non-combustible substrate, provided these finishes are not used in exit staircases and exit passageways. The main concern is that all protected routes meant for escape of occupants shall be kept free of combustible finishes. The above finishes include material such as gypsum board.

Non-combustible boards, for example gypsum boards, which meet the requirements of Cl.1.4.71 are allowed to be used for the construction of smoke-stop lobbies, exit staircases and exit passageways.

Explanations & Illustrations

Clause 3.14.1a. : Roof construction

Roof construction to buildings under PG I usually use timber rafters and purlins for tiled roofs. Rooflights of combustible materials are usually used for lighting purposes. Generally, buildings under PG I are small in area and low-rise. For semi-detached and terraced houses, the separating walls would be brought right-up to the underside of or above the roof coverings to prevent spread of fire.

Roofs of building under PG II may consist of dome, flat, pitched roof and other types. Roof covering may include mixture of combustible and non-combustible materials, e.g. slate, clay tiles, glass, rigid plastic. It is quite common to find hardwood timber trusses, purlins etc. being used in the roof construction. The term “roof covering” is used to describe construction which may consist of one or more layers of material, but does not refer to the roof structure as a whole. Roofs which may have different construction can be broadly grouped under the following:

1. Roofs over common corridors and means of escape. As these areas are meant for escape, it would be preferable that they be constructed totally of non-combustible materials.

2. Roof over apartment/maisonette or penthouse units.

3. Roof over linkway between buildings.

4. Roof used as terrace or floor open-to-sky. The roof covering should be of non-combustible materials to eliminate any fire risk arising from a fire involving the covering.

5. Roof over balconies

Roof can also perform two functions:

1. to contain a fire or prevent its penetration from an external source; and

2. to ensure that the external covering does not contribute to spreading of fire so that an adjoining roof might be in danger.

RC roof would be able to satisfy the above functions. However, traditional roof coverings such as tile, slates, metal roofing sheets etc., combined with timber trusses/purlins and combustible insulation materials would have a greater tendency to allow spread of flame. Rigid plastic or thermoplastic materials such as polycarbonate shall not be used. Similarly, thatched roof shall also not be used. Traditionally, tile roof construction requires timber battens and purlins for securing the tiles. However, the risk of fire spread via such timber members is taken care of by the provision of separating wall between residential units.

Explanations & Illustrations

Clause 3.14.2b. : Provision for buildings not exceeding four storeys

The provision of cavity area barrier is to prevent the spread of fire in the roof spaces. Any service penetration to the cavity barrier shall be fire-stopped.

The cavity barrier shall have minimum ½-hr fire resistance rating.

Clause 3.14.2c. : Provision for buildings not exceeding four storeys

Where false ceiling is not provided, the underside of the roof would be considered as the ceiling to the space below. Hence, there is a need to control the surface flame spread of the exposed underside of the roof construction.

Explanations & Illustrations

Explanations & Illustrations

1. It is recognised as an alternative means to protecting timber construction in buildings.

2. However, we have to understand the limitations on the use of flame retardant chemicals for upgrading of fire resistance and/or surface spread of flame rating of combustible materials. The limitations are as follows:

   1. The chemicals may deteriorate after exposing to the environment for a long duration. After such, the fire resistance performance or the surface spread of flame rating may be adversely affected over time.

   2. The inherent property of the flame-retardant chemical to resist fire spread may be affected when cleaning agent is constantly applied to the surface of the combustible material.

   3. There is no specific method and control of treatment of the flame- retardant chemical. This would lead to poor performance as a result of shoddy construction of the materials.

   4. There is no certainty on the duration for which the fire property in a material applied with such a chemical can last.

3. For buildings which are not under Conservation, the use of timber materials should be carefully considered and should be avoided where possible.

4. Building owners and occupiers should be made aware of the above mentioned limitations on the use of flame retardant chemicals. In the course of using the premises, building owners and occupiers shall not do anything to cause the retardant treatment to timber members to deteriorate.

5. For lining of walls and ceilings, and construction of mezzanine floor, flame retardant chemicals shall not be used to treat the timber members or other combustible materials to meet surface flame spread and fire resistance rating requirements respectively.

Explanations & Illustrations

All the internal non-load-bearing walls in the residential units shall be constructed of non-combustible materials. Materials for surface finishes of all the walls, non-loading-bearing, separating and compartment walls shall comply with Cl.3.13.5 and Cl.3.13.6.

Explanations & Illustrations

To separate areas undergoing A/A works from other occupied spaces, non-combustible partition is permitted instead of fire rated construction. However, the non-combustible partition shall be brought to the underside of the floor slab to segregate both spaces. This will help to prevent spread of smoke and fire which may be originated from the A/A works.

Explanations & Illustrations

Clause 3.15.19a.(1) : Use of plastics in building construction

1. There are various types of air supported or pneumatic building. Air supported structures are used for commercial and industrial applications, such as dining area, warehousing and manufacturing processes, for the agricultural and horticultural industries etc.

2. The membranes used for the air supported structures are usually nylon, plastic, PVC or polythene sheet material, which are combustible in a fire.

3. The main concerns are:

   1. the likelihood of the collapse of the roof owing to lack of pressure inside the structure or during times of emergency;

   2. the combustibility of the structure itself; and

   3. the collapse of the roof may cause panic and difficulties to occupants escaping during times of emergency.

4. In view of the above, proposal for air supported structure shall be evaluated separately and SCDF’s consent shall be obtained before making building plan submission.