What choices are there in fire resistant insulation?

[Adam Aglionby]

Radiant barriers or whatever foil faced things seem to be called , seem to be a matter of belief over physics lot of the time.

Thanks to a pistonheads poster of long ago for this succinct explanation:

`You need to multiply the resistance by the thickness (which effectively gi ves you the U-value), to get an idea of how much heat loss it's preventing. Multifoils have a very good resistivity, but very little thickness, so the total insulation effect isn't all that amazing. By comparison, a PIR foam like Celotex has a pretty good thermal resistivity and quite a bit of thick ness, so multiply the two together and you're looking at something much mor e effective`

Guessing this is the catch with aerogels, good thermal resistance , but thi n sheets, means to build up reasonable insulation makes cost climb very qui ckly.

Vacuum on a roll isn`t in the B&Q insulation aisle, wonder what fire perfor mance would be like?

[Martin Brown]

Radiant barriers combined with a layer of insulation are effective if the temperature difference across them is >30C or more above ambient. The foil layer equalises the temperature on the cool side and is a poor radiator which means a slower ingress of heat.

Celotex with a layer of aluminium foil gets you the best of both worlds. The foil needs to be facing an air gap or it does nothing much.

It is the cost and difficulty to make an aerogel that really hurts. Retail for silica aerogel is presently about $200 per cubic inch.

[tabbypurr]

If VIPs are impractical would asking about them be vacuous?

NT

[Roland Perry]

In message , at

07:20:20 on Fri, 30 Jun 2017, Adam Aglionby remarked:

It sucks

...the fire into itself.

[jrwalliker]

Its not quite that bad. For example:

John

[jgh]

I've been collecting offcuts of solid foam insulation panels to insulate under my kitchen floor/the cellar ceiling, ie:

but have been wondering whether to change what I should use.

[Tim Watts]

When put on wood, it's unlikely to make the situation any worse. Wood burns better than this stuff, one it gets going.

The only downside is *if* there is a small fire on it, the fumes and smoke are volumous and evil.

But do use fire rated canned foam if using any canned foam - the non FR stuff is nasty.

[The Natural Philosopher]

No. Its perfectrly safe in that sort of situation.

remeemer to seal it all with foam though and you really want a waterproof vapur barrier on the top, assuoimng its the house that is to be warm, and not the cellar :-)

[jgh]

Ok, I'll start keeping an eye out for off-cuts of "pondliner" as well. :)