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Ben Jaeger Posted: Sep 14, 2010 12:10 AM	foam in rafter question Mason, I have a job Im bidding on its an older 2-story home completely gutted. My question has to do with the roof venting. In the second story the customer wants me to spray 3"cc on a 4' high knee wall and 5"cc in a 2"x6" ceiling rafter from the knee wall up to the peak. He is then planning on doing a dry blown attic insulation on the attic floor behind the knee walls. With this setup do I have to install vent chutes or is there a way he can do an unvented roof system? If I install the chutes up to the peak, how do you seal everything up top with out the conditioned air leaking out?
mason Posted: Sep 15, 2010 08:31 AM	The cellulose insulation behind the kneewalls would need to vented, but not the sprayfoam area. Just keep those two areas sealed and separated from each other.

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Comments

Ben Jaeger

Posted: Sep 14, 2010 12:10 AM

foam in rafter question

Mason,
I have a job Im bidding on its an older 2-story home completely gutted. My question has to do with the roof venting.

In the second story the customer wants me to spray 3"cc on a 4' high knee wall and 5"cc in a 2"x6" ceiling rafter from the knee wall up to the peak. He is then planning on doing a dry blown attic insulation on the attic floor behind the knee walls.

With this setup do I have to install vent chutes or is there a way he can do an unvented roof system?

If I install the chutes up to the peak, how do you seal everything up top with out the conditioned air leaking out?

mason

Posted: Sep 15, 2010 08:31 AM

The cellulose insulation behind the kneewalls would need to vented, but not the sprayfoam area. Just keep those two areas sealed and separated from each other.

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