Explanations & Illustrations

Clause 3.7.1 : Requirements of compartment walls or compartment floors

Section

Figure 3.7.1

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 1^st storey shall not be penetrated by any openings or services even if:

a. such openings are provided with fire doors; and

b. the services are in protected shafts.

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

a. doors

b. protected shafts

c. ventilation ducts

d. pipes

e. 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

Clause 3.7.2 : Openings in compartment wall or compartment floor

Figure 3.7.2 - 1 : Door opening in compartment wall

Section

Figure 3.7.2 - 2 : Protected shaft opening in compartment floor

Figure 3.7.2 - 3 : Fire damper opening in compartment wall

Section

Figure 3.7.2 - 4 : Pipe penetration in compartment wall

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:

a. doors to protecting structure under Cl.3.8.6;

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

c. 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:

a. 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;

b. 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.

c. 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 3.7.4. : Compartment wall - roof junction

Section

Figure 3.7.4 - 1

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.

Axonometric view

Figure 3.7.4 - 2

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

Clause 3.7.6 : Non-combustibility of compartment walls or floors

( No illustration )

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:

a. floor finishes

b. wall or ceiling linings complying with Cl.3.13

c. 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).