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phil · Posted: Wed Sep 30, 2009 4:10 pm Post subject: spray foam

Has anyone used spray foam insulation,does it stop condensation,and would it stick to tin sheets any information would be helpful.

dara · Joined: 01 Aug 2007 Posts: 186 Location: Mayo

Hi Phil, the only problem i've come across with spray foam is that it can act as a bridge - damp can cross it. It will stick to anything but you get better results from the cure if you lightly wet surfaces first. It sounds like you've got the same problem with dripping tin as I have. A friend who's in the cladding business tells me that I should joist and line the ceiling with light ply and then seal it. He reckons the problem is not the tin but the damp ambient air circulating in the shed being drawn to it. If you cut off this you won't get the problem he says. I also considered getting it sprayed but he says that the damp will be drawn to the rafters - especially to the fixing points and that this will rot in time...
The other alternative is to take off the tin and lay over a breathable felt, leaving an inch or so gap between the two. I've done this in the pig pens and they are dry and reasonably cosy.

phil · Posted: Thu Oct 01, 2009 3:44 pm Post subject:

Thanks for that,to take the tin off so that i could use it again i would have to sacrifice the timbers, so new wood and membrane cost about the same as spraying.I will try the plywood it will be a lot easier and cheaper.

dizandstell · Posted: Thu Oct 01, 2009 9:23 pm Post subject:

Hi Phil
I helped a mate spray foam the inside of his barge. Once the foam had cured it was coverd with Oak sheets. As far as i know, he hasnt had any problems with damp or thermal bridgeing.

phil · Posted: Thu Oct 01, 2009 9:32 pm Post subject:

Ive ordered the plywood sheets now so will try that first, hopefully that will do the job.