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I have a friend who had an addition put on that has a cathedral ceiling.
Last winter he had an ice dam build up that ruined the drywall on the inside walls and ceiling. There are soffit vents but no ridge vent. Can we tear off the shingles, add 1×2’s on top of the decking over the rafters, then add another layer of decking and then shingle. Should we drill holes in original decking to allow moisture to escape to the new ridge vent. The rafters are 2×6 on a 4/12 pitch spanning eight feet.
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Replies
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Hi Scott,
That's a small room if the span is 8'. Or is it 8' from the sidewall to the centerline of the room?
Your objective is to create a properly vented space and a cold roof, correct?
Then tear off the roof deck and install the bay liners. If you're careful, the material can be re used. Your idea of creating an air draft with 1x2's is okay, except 1x2's seem a lil "wimpy." If you go that route, beef them up.
Also, I would install flashing in conjunction with the membrane. That's along the eave line. On low slopes in cold climates its a good hedge against
ponding.
But, hey wadda I know...(classic BT!)
Dan-O
*I think you can add on top. If your roof sheathing is OSB I think I would remove it . OSB is like a vapor barrier. If you leave your existing sheathing I would definitely add holes.Now if it were my house I would tear out the existing sheathing and put a layer of tyvek over the rafters. Then add a 2x2 on top of the rafters, then your new sheathing. Leave the tyvek long on the eave end and slit it down the middle of the rafter starting at the outside of the top plate downward. Fold it down between the rafters and staple or tape it to the side of the rafer. Use a continuous vent at the ridge. Now you have a 1 1/2" air space and a well vented roof.steve
*This might be one of the few cases where I'd say dense pack....with no venting.....would be a better retrofit. Jeff
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I have a friend who had an addition put on that has a cathedral ceiling.
Last winter he had an ice dam build up that ruined the drywall on the inside walls and ceiling. There are soffit vents but no ridge vent. Can we tear off the shingles, add 1x2's on top of the decking over the rafters, then add another layer of decking and then shingle. Should we drill holes in original decking to allow moisture to escape to the new ridge vent. The rafters are 2x6 on a 4/12 pitch spanning eight feet.