In article .com
, sm_jamieson writes
They used ISO super 9 style foil/fleece insulation in a loft conversion
on DIY SOS last week.
It appeared to be stretched over the loft rafters leaving 50mm-ish gap
behind, Then battens (38mm looked like) nailed through it onto the
rafters, and plasterboard over the battens. Thus leaving suitable air
gaps etc, but where it's squashed by the battens the insulation must be
poor.
But you get a much thinner roof than with celotex. Seeing a neighbours
loft conversion where you could hardly stand up a while ago, made me
think.
And what about using it in normal roofs. If it's evquivalant to 75mm
celotex, my extension roof design could be a lot thinner.
Is this stuff proven, and would the BCO pass it ?

IMNSHO the chances of this stuff meeting the insulation level of 75mm
Celotex in a real life situation is some where between zero and a a very
small thing.

Even if you believe the spiel, you need static air in the (uniform) gaps to
meet the claims so if you vent the outer air space, next to the roof, as you
should then there is no chance whatsoever of meeting the claimed
performance.

I have seen it used and passed by a BCO but that's not to say it is a
performance insulation system. If you want it effective use Celotex, if you
just want a box ticked then use whatever you can get away with.

HTH
--
fred
Plusnet - I hope you like vanilla