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Rifraf
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# Posted: 21 Feb 2012 13:08
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I'm still trying to figure this out. If theres a roof leak.. how do you know ? Sounds to me if you do this you should have a plastic roof deck 
The other concern is, what happens when either a new roof is put on or a roof patch is done.. wont the new nails puncture the foam and cause a place for water to pool ??
Thanks in advance guys, im ready to insulate and cannot find these answers online. My prefab shed has no ridge vent so I almost have to go foam or modify my roof.. just curious what I have to look forward to.
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Icebear
Member
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# Posted: 22 Feb 2012 01:57
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I have sarking nailed on top of exposed rafters. I layed purlins over the sarking and installed foam between the purlins. There is an air gap above the foam and the cavity can breathe - although who knows if it actually will breathe. PT ply over the purlins, then felt, and shingles.
My fascia isn't on at the moment and the nails holding the shingles have penetrated the ply and into the foam. Absolutely no water coming through however - we have had big storms and it is completely dry and well sealed.
I'd happily do it this way again. Not sure if asphalt shingles make this better than other materials as they essentially stick together and form a skin...
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Montanan
Member
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# Posted: 22 Feb 2012 12:57
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We have a similar set-up. Interior of the cathedral ceiling is hand-cut 2x6 pine decking. On top we put asphalt roofing paper, then laid purlins and installed foam insulation sheets between the purlins, and then put our metal roof on- fastened to the purlins with a small gap for air circulation. So far, it's nice and dry...and we've had PLENTY of rain and snow.
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