Spraying lycene foam under roof. Bad?


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Old 12-15-09, 12:39 PM
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Spraying lycene foam under roof. Bad?

Just got an estimate for lycene foam which is sprayed in the attic under the roof and creates a sealed off attic - even the sofits are sealed up. Any danger to the roof/shingles by doing this?

Kevin
Chicago
 
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Old 12-16-09, 07:02 AM
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Attic

May or may not be good. Normal attic construction requires ventilation at the eaves and ridge with adequate insulation on top of the ceiling of the living area below.

Why do you want to insulate under the roof? Just curious. Seems like a lot of additional expense.
 
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Old 12-16-09, 07:34 AM
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Insulating conditioned attics

Check out the .pdf here:

Unvented Roof Assemblies for All Climates
 
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Old 12-16-09, 05:43 PM
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Why am I doing this? Because the house is 30+ years old and the little bit of loose insulation on the floor of the attic is nowhere near enough. I could easily add more fiberglass or blow in some cellulose, but I've heard great things about the foam. I just worry about spraying the underside of the roof - attic ceiling. I know I'm going to need a new roof in the next 5-10 years too. The contrator said he will spray the soffits with foam and create a tight envelope. I worry that condensation will develop. It's 12 degrees right now in chicago and my attic is brrrrrr cold.

Mike thanks for the pdf. Sounds like they say the foam will be good for my climate if installed correctly. Unless I read it wrong.
 
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Old 12-16-09, 07:55 PM
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Making the transition from insulating the ceiling to insulating the roof deck requires a minimum of insulation as there is no venting to remove the heat that gets through. Thus one or two inches of Icynene will not be enough. Experts are suggesting we will need r-50 in our ceilings, even 40 will require a complete fill of a 2x6 rafter. And the rafter itself needs a good coat to reduce the thermal bridging it causes. Putting high r-values flat on your attic floor can easily be done and there will be no issues about replacing any/all of the spray foam when the new roof goes on. No, the jury is still out on foam applied to the bottom of the roof deck.

Also, Google "icynene problems" to see if others have had any issues with the product. I'm not a pro on foams, but applying them in the winter has to be a concern for quality, expansion, and adhesion. IMO

Bud
 
 

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