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Cavity Fire Barrier on a roll

Project Name: Cavity Fire Barrier on a roll

Company: Tenmat

Sector: Commercial 

Technology: Timber Fire Safety


The development of this product began in 2013 when the NHBC and the Building Research Establishment undertook a large scale program of combustible wall / cavity fire tests, this program followed a number of high profile fires within which the fire rapidly spread around buildings which had combustible materials within the wall cavities. Even when traditional fire barriers had been present eg cavity socks and timber battens these did not appear to produce the restrictions to the spread of fire that was expected.

Tenmat were part of the technical team in this project. It quickly became apparent, after the first few fire tests, that poor site installation resulting in gaps within the traditional fire barriers was the cause of the problem. At this time Tenmat set about the development of a product which would still perform when poorly installed but could also be installed onto panels prior to the delivery to site, thus reducing the need for relying upon the skill of the site labour. The new Tenmat intumescent product was then tested and compared to the traditional fire barrier solutions at BRE and was found to provide 100% fire performance even when the traditional methods of fire barriers failed. These results were published by the NHBC in their NF51 document / report relating to the spread of fire in combustible cavities.

The Tenmat product is a 75mm wide *6mm thick intumescent strip which is made from a unique material, this material unlike most other intumescent materials, only expands in one direction and unlike other intumescent materials, uses mineral fibre as the binder which then requires only a very small amount of organic material within the composition, this uniquely, makes the material very low smoke and halogen free and therefore is preferred by Fire brigades who have to enter a burning building.

Originally the Tenmat product was designed to rapidly expand and seal a 50mm gap when exposed to the heat of fire, this was then increased to 65mm which will be discussed later. The ability to expand from 6mm to 50mm with no additional support allows the wall cavity to be largely "open" allowing free movement of air throughout the whole cavity and negates the need for complex cavity trays, fire socks, weep holes and air bricks which often create their own problems within a wall cavity due to the potential for moisture bridging. As the need for the complex traditional "site installed" systems had now been negated then this led to the Tenmat product being readily installed offsite, this being helped by the robust nature of the product and the security of the fittings used which unlike traditional methods could easily withstand transportation and on-site abuse.