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Condensation in a non-vented cathedral ceiling

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Drayton Lester
2/6/2006
I need to reroof my 30 year old home that has a cathedral ceiling with no ventalation. It has 8" of batt installation between ceiling and plywood deck with 16 year old fiberglass singles. Will I always have a moisture problem because of no soffit or cable ventalation? If I install a metal roof, what can be done to insure I will not have a moisture problem. I'm looking at a metal shake product that is engery star rated.
Allan Reid
Dura-Loc Roofing Systems, Inc.
2/7/2006
The building code requires a minimum of 1" of vertical free air space between the insulation and roof covering. Tests our associ8ation just completed at DOE Oakridge proved that the air space doubles the savings that energy star provides and provides a 70% reduction over shingles. If you have had moisture problems then I would remove the old shingles to inspect the decking. I also suspect that you may not have an interior air barrier and although not as critical in your area, warm heat escaping will condensate. I would then recommend a breathing type underlayment, vertical strapping to provide the air space and then choose a product that installs on horizontal strapping. Make sure the system has a vented eave and ridge strip. Hope that it is our shake product that is energy star rated.
Guest User
2/14/2006
You say that an interior air barrier is not as critical in my area for my cathedral roof. If an air barrier with soffitt and ridge vent were installed, would this be practical and when would I see the energy savings (summer or winter). Would this be a better solution or should I just go with your earlier reply and yes with an energy star rated metal roof.
Allan Reid
Dura-Loc Roofing Systems, Inc.
2/21/2006
An air barrier is on the ceiling side of the room. A moisture barrier goes between the roof covering and the insulation. You need to stand the roof covering off the insulation a minimum of 1" and ventilate the space. This can be done with vented profiled closure strips that fit the metal profile. And sya yes to an energy Star rated roof and save the energy and annual costs.
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