Following some enquiries....
A number - most likely all of the ebay sellers, are selling the flammable version of polystyrene for building insulation purposes, which in my view, knowing how it can burn, is very dangerous. Anyone know what the building regulations have to say about the use of such insulation?
The regulations for domestic properties are here:
My new extension (not a diy build, sorry) has 4in of polystyrene in the concrete floor. It would need to be a good fire burning for some time to get through to that.
under screeds is where it belongs, and is very good value for money.
In walls, use batts. In airtight spaces use rockwool.
For everything else there is celotex.
Phil L pretended :
Yes, but unlike wood, which tends to char - this stuff is very flammable. Once alight it feeds the flames and rapidly spreads and there is a flame retardant version available for not much more cost. Agreed, under a slab there is no risk, but the ebay sellers are suggesting it (the none flame retardant version) can be used in lofts.
One readily burns and drips burning plastic, the other just melts away from the flame. I was just surprised they were suggesting the flammable version could be used above the slab.
Whether flammable or not, don't let electrical wiring touch the polystyrene or the insulation will degrade.
In the loft it is separated from habitable areas by ceiling, which should meet the requirements for spread of flame. Fires very rarely start in the loft.
Colin Bignell
Completely untrue.
Chimneys with blown pointing, electrical stuff chewed by rats or mice..
all very common. Thatch even more so with added risk from chimney fires.
Arguably polystyrene won't make this *worse*, but even so...
It is estimated that 90% of domestic fires are not reported, as the householder manages to extinguish them without help. Of the remaining
10%, 47% start in the kitchen, 28% in the bedroom, 17% in the living areas and just 6% in all other places. As it is improbable that people will notice a loft fire in time to deal with it themselves, this implies that fires starting in the loft represent some unknown proportion that is only known to be less than 0.6% of the total. I would class that as rare.Colin Bignell
You missed cable damage caused by contact with polystyrene. B-)
As postage is a problem, I got mine from the local Wickes instead. The stuff is still commonplace, and there's nothing "dodgy" about its sale.
Insulation and fire protection can't be considered in isolation. There's no major problem with using a flammable component, provided that it's protected from fire applied to it, and the effect it might have in either generating fumes, or in propagating a fire, are considered. My small workshop's roof and walls are insulated with it, but I won't be using it in the bedroom ceilings. The '60s & '70s fondness for it as ceiling tiles and cornices horrify me.
Not like the polystyrene ceiling tiles in the kitchen of the first house my wife and I lived in. One of the other sharers set fire to the lot once. I'd never want them in any house of mine.
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