Hi,
I'm putting up insulation in a workshop with a single pitch corrugated steel roof on perpendicular 8" tall (200mm) rafters.
I'm using 2" celotex and 2" loft insulation between the rafters with plasterboard underneath.
Should I leave a 2" gap at the top although I'm not sure how that works if the flow down the underneath of the corrugate hits every rafter as it goes.
Do I need to put the loft insulation over the celotex? Or the other way around?
I was thinking put the celotex up high enough for the 50mm gap above and seal it in with foam then have a 50mm air gap then the loft insulation underneath flush with the bottom of the rafter, on the plasterboard.
200mm of;
50mm air flow, 50mm sealed celotex, 50mm air gap, 50mm loft insulation.
(A richer and more intelligent person would have used 100mm loft insulation.)
Are there any possibilities of condensation below the the celotex if sealed above? And in the loft insulation unable to escape?
There aren't any condensation problems, but it's currently been a single brick thermalite building with a tin roof, so who would?
The better thermal option might not be the best option, though it's mainly just sawdust in there, no wet towels or anything...
Thanks for any help.
I'm putting up insulation in a workshop with a single pitch corrugated steel roof on perpendicular 8" tall (200mm) rafters.
I'm using 2" celotex and 2" loft insulation between the rafters with plasterboard underneath.
Should I leave a 2" gap at the top although I'm not sure how that works if the flow down the underneath of the corrugate hits every rafter as it goes.
Do I need to put the loft insulation over the celotex? Or the other way around?
I was thinking put the celotex up high enough for the 50mm gap above and seal it in with foam then have a 50mm air gap then the loft insulation underneath flush with the bottom of the rafter, on the plasterboard.
200mm of;
50mm air flow, 50mm sealed celotex, 50mm air gap, 50mm loft insulation.
(A richer and more intelligent person would have used 100mm loft insulation.)
Are there any possibilities of condensation below the the celotex if sealed above? And in the loft insulation unable to escape?
There aren't any condensation problems, but it's currently been a single brick thermalite building with a tin roof, so who would?
The better thermal option might not be the best option, though it's mainly just sawdust in there, no wet towels or anything...
Thanks for any help.