On Sat, 30 Sep 2006 22:38:05 +0100 Hugo Nebula wrote :
or use this spiral wrap from screwfix. It is silver bubble wrap and is
designed exactly for your purpose.

http://www.screwfix.com/app/sfd/cat/...62194&ts=16185

Equivalent to 33mm polystyrene!!!?!!?
That'll be UNexpanded polystyrene then.

I was sceptical too, but it appears to be correct. The R-value of
Alreflex (the nearest equivalent I could think of) with no cavity
either side is 0.15m2K/W; the R-value with cavity both sides is 1.56,
so the R-value with one side exposed must be 0.93. Multiply that
figure by the conductivity of polystyrene (0.037W/mK) and the
equivalent thickness is 34mm so they're not far off.

Note that the following BRE document casts doubt on the TRADA figures
being quoted for this sort of insulation

http://www.planningportal.gov.uk/PpW...n_july2005.pdf

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk