Standard PB v foild backed v moisture resistant

Postby Kevin1996 » Thu Aug 08, 2013 7:53 am

I had a leaky flat roof in the living room ext and I have decided to re-plasterboard the whole area about 10ft x 8ft. I will put the board up then get the plasterer who lives near by to skim it.

I am a little concerned that there is virtually no air gap between the insulalion and the roof decking. It was suggested that if I put foil backed up then I would get less possibility of condensation due to moisture migrating through the PB. If that is true would it be worth considering putting up moisture resistant PB?
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Simply Build It

Postby welsh brickie » Thu Aug 08, 2013 4:47 pm

you need to vent the flat roof by either installing a strip vent, or soffit vents. The insulation should be 25 to 50mm thinner than the roof joists to allow airflow, then you can use ordinary plasterboard
welsh brickie
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Postby Kevin1996 » Fri Aug 09, 2013 9:34 am

I know this is not a plastering question, but I will either have to take some of the insulation out or somehow squash the insulation to force a gap under the decking. I assume the air gap has to be above the insulation.
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