6.2.9 Fire resistance
Timber walls and panels shall control and resist the spread of fire and smoke. Issues to be taken into account include:
- cavity barriers and fire-stopping
- services
- fire resistance of the wall or panel.
All building elements should have adequate fire resistance. Materials in accordance with Building Regulations are acceptable; other materials should be assessed in accordance with Technical Requirement R3.
For guidance on the prevention of fire during construction, refer to Fire Prevention on Construction Sites, published by Fire Protection Association (www.thefpa.co.uk), and guidance from the Structural Timber Association (www.structuraltimber.co.uk) under the Site Safety Strategy, including the 16 Steps to Fire Safety and the Design Guide to Separating Distances.
6.2.9.1 Cavity barriers and fire-stopping
The installation, position and materials for cavity barriers and fire-stopping should be in accordance with the relevant Building Regulations and the design.
Where cavity barriers do not align with structural framing members, additional studs and full-depth noggings may be required to provide a solid backing for the cavity barrier; alternative designs should be supported with appropriate evidence.
Horizontal and vertical cavity barriers should be protected by DPCs arranged to shed moisture away from the sheathing. Horizontal cavity barriers in masonry cladding, except under eaves, should be protected with:
- a DPC tray with a 100mm minimum upstand, or
- a polyethylene-encased cavity barrier with a 100mm minimum upstand.
Horizontal cavity barriers in lightweight cladding should be protected by cavity trays, DPCs or flashings as appropriate.
Figure 36: Fire-stopping and compartmentation at compartment wall/roof junction
Figure 37: Horizontal cavity barrier protected with DPC
Figure 38: Vertical cavity barrier protected with DPC
6.2.9.2 Services
Only the services shown in the design should be installed in separating walls, and:
- service outlets should not impair the fire resistance of floors and walls
- service mains should not pass through separating wall cavities.
Notching or drilling of structural timber members should be carried out as detailed in the design. If these details are not available, the designer should be consulted before such operations are begun.
In Scotland, services are not permitted within a timber framed separating wall.
6.2.9.3 Fire resistance of the wall or panel
Timber frame walls should have adequate fire resistance in accordance with the relevant Building Regulations.
Timber frame systems should be supported with representative evidence to appropriate standards. Supporting evidence should be relevant to the materials, systems and details proposed.
Last updated: 2nd January 2025