TRA issues new fire safety guidance for trussed rafter ceiling constructions

The Technical Card from the Trussed Rafter Association
The Technical Card from the Trussed Rafter Association

New ceiling construction guidance has been published from the Trussed Rafter Association (TRA), which show fully tested solutions for fire safety in new homes with trussed rafter roofs.

The new TRA guidance provides builders with design options to meet the fire resistance requirements for trussed rafter ceiling constructions in individual homes.

When followed correctly, these construction details are shown by test to provide 30 minutes’ fire resistance, in line with European Standards (and therefore, by default, the less onerous British Standards). It is the first time such guidance has been published by the TRA to the new homes industry.

Nick Boulton, chief executive of the TRA, said: “Health and safety, and fire safety in particular, is always on our agenda. Two years ago, TRA members moved away from older British Standard design codes and committed to Eurocode 5 (EC5) design solutions for trussed rafter products and metal web components. Now with these fire safety solutions, we have again decided to test our products against more rigorous European requirements and move the industry forward to a higher and safer standard.

“Obviously, it is up to the building designer to decide which evidenced fire resistance solution is most appropriate for the homes they are designing. But fire testing has become much more rigorous since the Grenfell Tower tragedy, so we decided to offer some additional fully tested solutions that we know will meet the current fire resistance requirements and boost safety in new homes.

“We are committed to educating the sector on good practice and will continue with our programme of testing for all relevant products, so that we can stay ahead when it comes to safety.” 

In the case of a house fire, trussed rafter constructions need to maintain their structural integrity, load-bearing capacity, and resistance to the transfer of excessive heat across the roof structure. The combination of these factors determines the fire resistance of the floor or ceiling.

Therefore, a series of fire resistance tests were commissioned by the TRA to cover four different design solutions for trussed rafter ceilings in single occupancy dwellings. These include options for homes with more than one storey and new homes with rooms in the roof.

Fire tests were carried out to EN 1365-2 standards. The construction solutions proposed in the TRA guidance were found to meet all the fire resistance requirements for the scenarios identified in the Building Regulations.

Four construction solutions are detailed in the TRA Technical Card, including information on the truss type, plasterboard, battens, insulation and additional components. The details of the fire test and summary of supporting test evidence is also provided for each.

For a free copy of the technical guidance, contact your TRA member trussed rafter supplier, which can be found at www.tra.org.uk.