insulation in sloping roof

Postby Dan Stewart » Tue Dec 06, 2011 10:30 pm


I am looking for some (retrospective) advice on insulating a sloping roof. We have a 1 and a half story stone built house with bedrooms in the roof space with dormer windows. In my wisdom when stripping out the room I insulated in between the roof joists (on the sloping sections) with space blanket style insulation. I am wondering if this was a mistake as it is likely to be reducing air flow which I think is equally if not more important. Could anyone advise if I would be petter to pull this out from the small loft space at the very top of the roof pitch? If so is there anything I can do now to insulate better?

Thanks for your help

Dan Stewart
Posts: 15
Joined: Sun Feb 08, 2009 9:12 am


Simply Build It

Postby welsh brickie » Wed Dec 07, 2011 7:42 am

if the roof has a breathable membrane then its not a problem.If it isnt then its best to use kingspan or a celotex insulation.
welsh brickie
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Joined: Sat Apr 12, 2008 7:54 am

Postby xavi99 » Fri Dec 16, 2011 8:27 pm

I assume that you are referring to the air flow above the insulation on the cold side. This is only an issue if warm moist air can penetrate. If you have installed space blanket style insulation and have taped the joints then there should not be a problem.

Replacing with an alternative style of insulation may not cure this problem. Try looking on the insulation manufacturers website, they are usually very good.

Good luck,

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Joined: Fri Jul 29, 2011 12:01 pm

Postby Dan Stewart » Fri Dec 23, 2011 9:56 pm

Thanks all for your replies, I should have said the roof is a traditional sarking board and slate (no membranes) so I am assuming from your posts that this should be OK as the roof will be able to breath.

Thanks again for your help

Dan Stewart
Posts: 15
Joined: Sun Feb 08, 2009 9:12 am

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