Polystyrene Insulation

I have recently insulated under the timber floor (has a void about

18")., with slab polystyrene. (was free, and the sort used in flat roof insulation). The stuff was cut to fit the joists and is pressed down onto tanalised battens. Battens are roof lathes and the polystyrene is 50mm. Extra to this is cooking foil pasted onto the surface This cost less than =A32 for the whole room. . An attempt to duplicate aka Kingspan. No vapour barrier other than the foil and not over the joists.On top is new chipboard flooring. My question to you luvverly people is...IS THIS SAFE. Have I got to undo.
Reply to
ken70
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Polystyrene - fire safety - toxic fumes, bad news. Polystyrene - contact with pvc insulated wiring - hardening and cracking of insulation.

Reply to
dom

I think if your floors ablaze, the polystyrene fumes are the least of your worries;-)

good point about the PVC tho

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Reply to
rich_bike

Thank you for the replies, not sure whether to post at top or bottom. However, had the idea that the foil would delay spread of flames and flames would burn away from it anyway. Flooring is screwed down so not a big job to dismantle. Could have sworn Kingspan was Polystyrene with added foil, and is recommended for under floor. Also I notice Wickes sell Polystyrene for the same purpose. Is consulting the Local Authority Building Inspector FREE.??

rich snipped-for-privacy@hotmail.com wrote:

Reply to
ken70

Kingspan is polyurethane

Reply to
visionset

Most Kingspan/Celotex boards are polyurethane which is a much better insulator - 25mm PU is as good as or better than 40mm EPS

Reply to
Tony Bryer

If it is flooring grade insulation then chances are it is treated with a flame retardent anyway. So it will melt if you heat it enough, but ought not add to the spread of flames. So if you keepo it out of contact with any PVC it ought to be ok.

Note that kingspan etc are not the same - they are Polyisocyanurate (PIR) foam.

Reply to
John Rumm

No. It's foam with added foil, and twice the price of polystyrene. Presumably it smells sweeter when ablaze.

, and is recommended for

Reply to
Stuart Noble

================================ I did this same job about three years ago except that I used just the polystyrene without foil. I asked my local BCO about suitability and he said there were no problems with using polystyrene in this way.

I was aware from posts elsewhere that PVC wiring and polystyrene was a bad mix so I made sure that the wiring runs were kept separate from the polystyrene. As far as fire risk is concerned I don't think I've ever heard of a fire starting under a suspended floor so I think the risk must be quite minimal.

Cic.

Reply to
Cicero

It doesn't burn _very_ well, but it does catch fire. So I found out when using some of it to protect the walls whilst chopping some 1/4" plate with an angle grinder in-situ in the lounge.

:¬)

Reply to
PeTe33

One of its combusion products is cyanide, although I doubt you would be able to smell the almonds amongst the other things. You can smell it when you cut the sheets with a knife (it's probably a more complex cyanide-based molecule in this case).

Combusion products of polystyrene are pretty nasty too because it does a bad job of burning all the products, and you end up with significant amounts of unburned styrene, carbon monoxide, benzene, toluene, etc coming off. If it's old polystyrene, you also get combustion products from the incomplete burning of the CFC used to expand it, which can include hydrogen fluoride.

Reply to
Andrew Gabriel

Reply to
ken70

On 21 Dec 2006 04:06:05 -0800, a particular chimpanzee named "ken70" randomly hit the keyboard and produced:

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Reply to
Hugo Nebula

Thank you Hugo...lots to read....think I'm covered but checking with County Hall after the holiday. If not O.K'd cheapest way out would to paint on some flame retardent. Got the original info from a 'Which' DIY book (published 1999), should have come here first. :-)

Hugo Nebula wrote:

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Reply to
ken70

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