As these shelters are made of strengthened walls, floors, ceilings and specially designed doors, they must:
Not be hacked or drilled indiscriminately
Not contain certain finishes and fixtures that may be hazardous to shelter occupants during a war emergency
Have lighting, power socket outlets, telephone point and radio or television outlet points for external communication purposes
Details of permitted and not permitted works may be found in Chapter 7 of Technical Requirements for Household Shelters and Technical Requirements for Storey Shelters.