a. The surface of materials for roof covering and roof construction shall have a surface spread of flame rating not lower than Class 1, or Class A when tested in accordance with ASTM E108, except in the case of PG I and PG II, and in buildings that are protected throughout with automatic sprinkler system.
b. Composite panel used as roof covering shall comply with Cl.3.15.13.
c. Roof covering containing plastic shall comply Cl.3.15.19c.(7).
3.14.2 Provision for buildings not exceeding four storeys
Combustible material can be used for roof construction for PG III, IV, V and VII buildings which satisfy the following requirements:
a. the building shall not exceed four storeys;
b. the roof space between the roof and the ceiling shall be sub-divided by cavity barriers where required to comply with the relevant provisions of Cl.3.11,
and openings in cavity barriers shall be fire-stopped to comply with the requirements of Cl.3.12; and
c. if the underside of the roof serves as the ceiling to a room or space, the elements of the underside of the roof shall comply with the relevant provisions of Cl.3.13 for restriction of spread of flame.
3.14.3 Roof junction with separating wall and compartment wall
At junctions where the roof meets with a separating wall or compartment wall, the roof construction shall comply with the relevant requirements under Cl.3.6.3 and Cl.3.7.4 respectively.