Tenmat offer the first range of fire protection products to be successfully tested on metal web joist ceiling constructions
Metal web joists and light weight engineered joists are becoming increasing popular in the construction industry, particularly for home builds.
Whilst this type of joist does offer many great benefits over traditional solid timber joists, there has been a widely recognised problem of premature failure during a fire situation which endangers both the lives of occupants and firefighters.
Premature failure occurs when the fire enters the ceiling cavity and attacks the joists. Unlike solid timber joists which have a large degree of sacrificial material and can resist direct fire attack for up to 15 minutes following the breaching of the plasterboard protection, light weight joist system have little sacrificial material which can cause collapse within a few short minutes following a breach of the plasterboard protection, this has led to a very poor reputation particularly with firefighters.
Courtesy of Manchester Building control, this ceiling collapsed after 8 minutes
The major cause of the breaching of the plasterboard protection layer is the penetration of ceiling with recessed lights, ventilation valves and ceiling fans. Until now manufacturers of so called “fire rated products” have generally tested only with solid timber joists as light weight joists are seen as being too onerous and require a much higher level of fire protection and simply better products.
Building regulations require that products are tested with constructions that are representative of those used in application.
Tenmat have now tested a range of downlight covers, fire rated ceiling valves and ceiling fans in the most onerous 30 minute full scale loaded BS EN 1365-2 with metal web joist floor ceiling construction, which produced a result exceeding the 30 minute performance by a full 10 minutes and so can offer products which not only fully meet building regulations but will also allow the extended safe usage of light weight joists systems.
Metal web joist fire test ceiling with 7 large penetrations protected by Tenmat products.