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I have a finished attic, that needs to be updated. The pitched sides of the roof are sheetrocked & insulated, the ceiling is a suspended ceiling (will be sheetrocked) and the low knee walls are insulated and paneled (will be sheetrocked).

The pitched ceiling does not have rafter baffle venting. It does have continuous soffit vents, a full length ridge vent and a gable vent. I realize it's best if the soffit vents have air movement up to the ridge vent, however I'd like to avoid ripping out the sheetrock and insulation on the pitched ceiling.

Is there an alternative to the standard rafter venting that can be installed on old versus new construction?

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    What do you mean when you say it doesn't have proper venting- Does the insulation fill the entire cavity (allowing for no air movement)? Do you have issues with ice dams in the winter? – gregmac Nov 24 '13 at 19:27
  • @gregmac - may be a difference in terminology. What we refer to as proper venting is rafter venting - the extruded foam panels. The insulation is up against the roof board on the pitched ceiling, and we do get the occasional ice dams (would probably get more if we kept that room warmer). – Jason Nov 24 '13 at 22:05
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    If the drywall does not cover the entire ceiling, you may be able to gain enough access to compress the insulation a bit, and slide baffles into place. Is this possible in your situation? – Tester101 Nov 25 '13 at 13:16
  • @Tester101 - Unfortunately, the pitched ceiling is about 10 ft, so I'm not sure how I would place 2' ft baffles the entire length. – Jason Nov 25 '13 at 15:24
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    I think you can either do nothing, or face up to ripping open the drywall. Well - you could deck over the roof (leaving a vent space between old and new) on the exterior. Drywall is likely cheaper. – Ecnerwal Mar 26 '14 at 2:08
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Typically this type of structure is properly vented already as you described it. The pitched part of the roof is typically insulated tight with a 1" sheet of foam at the roof then friction fit unfaced. Then a plastic vapor barrier then drywall. Sounds like you're doing a roof so you might consider a foam roof substrate over the pitched rafters. Your existing Kraft face insulation could be causing tagger show because of leaks in the seams. Consider a vapor barrier paint for the interior.

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  • You're talking about a "hot roof" design, @20573? – TDHofstetter Aug 21 '14 at 6:00
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You have your baffles already installed, you just need to space them correctly. Remove the drop ceiling & the knee wall paneling to then wedge the rigid foam board insulation away from the roof decking.

You just need an inch or so away from the roof decking & the Sheet rocked portion is only 10', so you should be able to attack from both ends. Cut the rigid insulation into sections, if needed, so you can then slip in a shim to start backing the rigid foam away from the decking.

Continue spacing away from the decking with longer scrap pieces cut to a point on the end or even a broom handle until you can see a good gap up to the ridge & down to the soffit. You'll likely need to take out the knee wall to soffit insulation & ceiling to ridge sections to then reinstall correctly. Use what you already have in place & you'll notice a world of difference & not have ice dams again.

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