Wetherby Building Systems is one of the first EWI system manufacturers to gain BBA (British Board of Agrément) approval for grey polystyrene insulation.
EpsiTherm, a graphite enhanced EPS insulation board, is supplied by Wetherby as a main component of their Epsicon and Epsiwall external wall insulation (EWI) systems , which can both be used on new build and refurbishment projects. The product has undergone rigorous testing and has surpassed all requirements set by the BBA and ETAG 004.
The British Board of Agrément is the UK’s leading authority offering accreditation and inspection services to manufacturers and installers that supply the construction industry and has clear criteria when it comes to external wall insulation products.
The bond strength performance of the EpsiTherm insulation was tested in accordance with the MOAT 22 assessment method and exceeded all requirements. The insulation was examined as to how well the scrim adhesive adhered to the insulation and tests were completed for the two different finishes the BBA certificate covers; silicone render and dry dash.
Testing its adhesive abilities, EpsiTherm was pulled from a wall with increasing force, in both dry and wet conditions, to determine how much force is needed before the insulation starts to break away. Exceeding the set requirement, the product demonstrated a tensile strength of 0.291 Nmm2 in the silicone tests and 0.352 Nmm2 in the dry dash tests.
EpsiTherm was also tested for its water absorption properties, an important constraint to pass for products fitted to the exterior of any property. When testing the insulation by partial immersion, the water absorption coefficient was recorded as 0.31 Kg/m2, surpassing the requirement of less than 1Kg/m2 after 24 hours of partial immersion.
The pull out test ensured that EpsiTherm can withstand being mounted to the wall without cracking and splitting the insulation around the fixing. Mounted using Termoz CN fixings, the product once again passed this test with ease, incurring a failure load of 948 KN/m2.
EpsiTherm insulation comprises expanded beads of polystyrene that incorporate a graphite component, which are then fused together in a pressurised steam-heated mould. The inclusion of graphite ensures the product offers an enhanced thermal insulation material and using a thickness of just 90mm, EpsiTherm can meet required u-values without too much disruption to the external envelope.
Joe Ragdale, technical manager at Wetherby, comments: “Passing the BBA tests reassures housing associations, local authorities and contractors that they are specifying an industry approved product, making it the ideal cost-effective insulation material for housing refurbishments and regeneration projects.
“We have been inundated with requests for the grey EPS insulation, so the certification means we can now fulfil requests for projects to be installed with EpsiTherm under ECO and Green Deal schemes.”