Whilst the scale of failure at Grenfell Tower continues to unfold I am still struggling to understand how the materials on the exterior of the building were specified and by whom. An analysis of the Celotex RS5000 insulation raises worrying questions.
If you look at the Celotex website it states that their products are BBA (British Board of Agrement), CE (European Conformity), and BRE (Building Research Establishment) tested. Two certificate numbers are shown under the BBA insignia despite the BBA website indicating no such certificates exist. A search of the BBA certificates listed elsewhere by Celotex indicates that none were obtained for RS5000 i.e. this particular insulation has no safety certificate.
The BRE certification is used as the justification for using this material in facades over 18m in height. Reference is made to the BR135 performance specification. However this applies solely to a unique construction based on two 12.5mm skins of plasterboard on a lightweight steel frame, with another 12.5 mm of incombustible board, then the Celotex RS5000, and finally a further 12.5mm fibre cement facade panel. In other words the insulation has to be totally encapsulated in fireproof material.
Only if that construction is followed is the certification valid. The manufacturer even warns architects about this by stating that “The fire performance and classification report issued only relates to the components detailed and constructed in Fig 4. Any changes to the components listed and construction method set out in figure 4 will need to be considered by the building designer”. That’s another way of saying that if you depart from this specification - as the Grenfell Tower facade designer did - then the fire performance is invalid above 18m.
That leaves only the CE certificate. Celotex state that “CE marking confirms that our products fully comply with BS EN 13165 and that key performance characteristics have been verified through independent type testing”. One would therefore assume that since this is a product advertised for use in a fire rated construction then the fire aspects will have been tested. However when you drill down into the certificate only the thermal performance and compressive strength have been verified. The remaining ten categories simply state “No Performance Determined”. This includes Reaction to fire; Release of Dangerous Substances; Durability of reaction to fire against heat; and Durability of thermal resistance against heat. Nowhere does it tell you that polyisocyanurate releases a lethal gas in a severe fire condition. Put simply, this certificate leaves so much risk with the designer that I would have no choice but to refuse to use the product.
That then begs the question that I asked previously about the Reynobond panel. How is it possible for so many people involved in the construction of the Grenfell Tower facade to ignore the warning signs that both these materials were fundamentally unsuited for use on any high rise construction ?