Beating the panel

Andrew Lee panicked when the man from the Association of British Insurers told him that the only future for foamed polyurethane-cored sandwich panels lay in the knacker's yard. For the Hunter Douglas general manager, it was a dark moment. It could mean writing off a plant and surrendering a profitable product line.

Hunter Douglas had been making its lightweight panels since the 1960s. Then along came 9/11. To cover the cost of the destruction of New York's World Trade Centre in 2001, insurers hiked premiums and cut risk out of their portfolios. In the construction industry composite facade panels took a hit as insurers punished their association with several high-profile blazes in food preparation factories: polyurethane has many virtues, but fire-resistance isn't one of them. Premiums rose, and some new builds even had their freshly-installed sandwich panels removed and replaced.

The trouble with foam
If that wasn't bad enough, at the same time CFCs and HCFCs (chlorofluorocarbons and ydrochlorofluorocarbons) were being progressively banned from construction products. The foaming agents that gave polyurethane its vital insulating air bubbles also gave off CFCs/HCFCs. Unless the foaming agent suppliers found an alternative, Hunter Douglas wouldn't have a product.

Fortunately, they did, although the new foaming agent wasn't quite as good thermally or structurally, so satisfying the Building Regulations now required a slightly thicker sandwich. Getting over that hurdle, though, didn't solve the fire problem.

Lee did consider ditching foam-cored panels; after all, Hunter Douglas also makes plenty of sandwiches with more expensive mineral wool and polyisocyanate fillings. But polyurethane is lighter, so it's easier to install. It also produces a flat panel: mineral wool needs a greater density of filling to stay flat, and that reduces its thermal value.

Lee decided to prove the insurers wrong. Six months and £60,000 later, he had a panel equipped with steel rather than aluminium skins, intumescent strips around all the edges and better joint detailing. Last year, at its first attempt, the new panel passed the fire test that gains the all-important approval of the LPCB (Loss Prevention Certification Board). It also passed the Centre for Window and Cladding Technology's air leakage test, so it has the right seals of approval for the Regs as well as the insurers.

"It's a total wall solution," boasts Lee. "We've already got our first order for a hospital PFI. It's not huge, but it's a high-spec, high-value product – we're not looking for 100,000m2 contracts." Polyurethane-cored cladding, it seems, is back on the specifiers' lists.