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insulating cathedral ceilings


thunder's Avatar
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02-06-04, 03:55 PM   #1  
thunder
insulating cathedral ceilings

Can anyone tell me what's the proper way to insulate a cathedral ceiling so I don't end up with condensation problems? I'm building an addition and the rafters are 2"X8". thanks for any help.

 
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02-06-04, 05:07 PM   #2  
lori7
With the research that we have done since we have had all of our problems, it looks like the way to go is to get someone to blow in icylene foam insulation. That means no ventilation, which is what seems to be causing our problems. Good luck!

 
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NJ

02-06-04, 06:42 PM   #3  
http://www.certainteed.com/cvent/cvav00401p.html

This site show a "Flash FilterVent" where a roof meets a wall, if it is a shed roof. If it is a gable roof, then use a ridge vent. This along with soffit or eave vents in conjunction with styrofoam baffles between the insulation and the underside of the roof will provide you with enough ventilation to avoid any moisture problems.

 
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02-06-04, 07:05 PM   #4  
lori7
We had no foam in our roof when we built the house 18 years ago, just standard insulation. We have had problems with condensation every year. We tried the foam board, and that made no changes. We are not about to tear down our roof and completely rebuild it. We also are not going to tear down everything again and try reversing foam fiberglass and air space when a supposed expert told us to do it the way we did-- foam airway, then fiberglass. We are going all foam, the way log home builders do it up here. We have tried to many things with to much damage.

 
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02-06-04, 07:45 PM   #5  
Structural Insulated Panels (SIP) that are used on log cabin homes usually have a cold roof installed, if they use regular asphalt shingles. If they have cedar, slate or similar roof material, they do not need the cold roof but is still advisable that they install one. The reason for this is the way insulation, regardless which kind it is, retards heat flow is by retaining it. Asphalt shingles installed on a SIP without a cold roof will begin to cup and crack after the first summer. This is because the maximum temperature of asphalt shingles is no more than 175 degrees Fahrenheit and the shingles being installed over an insulated roofing system that is not ventilated will exceed that temperature.

 
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