All forms of construction must comply with the fire performance requirements laid down by national Building Regulations. SIP-based structures can easily meet or exceed the required levels, given the correct design, standards of manufacture and build-up. When considering fire performance in buildings, two stages of fire development must be recognised and reflected in testing – ignition and fire growth and the fully developed fire.
- BS 476-21 : 1987 Fire tests on building materials and structures — Methods for determination of the fire resistance of loadbearing elements of construction
- BS EN 1995-1-2 : 2004 Eurocode 5 — Design of timber structures — General — Structural fire design
- EN13501-2:2016 Classification of Fire Resistance
- EN1365-1:2012 Fire Resistance Test
Exceeding the Required Levels
The wall linings, typically plasterboard (although other types of fire-resistant board are available), provide SIP external wall fire resistance. Typically, one layer of 12.5mm Type F (fire/high temperature) plasterboard fixed to timber battens, forming a nominal service void, will provide 30 minutes of fire resistance to a SIP wall regardless of SIP type or core insulation material. 60 minutes of fire resistance to any SIP is achievable with two layers of 12.5mm Type F (fire/high temperature) plasterboard fixed to timber battens forming a nominal service void.
Unless the roof forms an escape route or is habitable space, roof structures do not generally require specific periods of fire resistance. However, if the roof is habitable, floor-to-room-in-roof space must provide 30 or 60 minutes of fire resistance.
Typically, floors are either metal web joists, timber ‘I’ joists or large room-in-roof trusses with fire resistance achieved in a similar way to the protection of timber joisted floors through the use of plasterboard. If the roof structure forms a means of escape, fire resistance requirements vary on a project-by-project basis.
A summary of fire resistance tests conducted on small and large-scale samples of SIP buildings is in the BRE Information Paper ref: IP21/10. These DCLG, the Department for Communities and Local Government funded tests were conducted at an independent laboratory to determine the performance of SIP systems exposed to realistic fire scenarios.