how high cellulose?

to get R38 in my attic, I'm going to need to blow in to a depth of almost 12". But, the joists are 8"... So, basically I fill between the joists, then over the top of them?
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You blow between the Trusses, which should be either 4" or 6" in special cases. And yes above them... here in Alberta Canada we Blow in a standard R-40.. you can go 24"'s if you want just don't do that near the outside edges. You need airflow from your Soffits over your insulation and out your roof vents. Along the bottom edges you should have cardboard Insulation stops..if you don't go get some from your local building supply. Don't blow over these it will stop the air flow!
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Barb wrote:

That's not a problem but cellulose is weak on moisture. It soak up moisture easy and collapse. Then R value crashes. Why not fiberglass? Even if cellulose is treated.
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I know there is a huge debate over fiberglass vs. cellulose, and I spent a lot of time thinking about it and researching it. For DIY, cellulose is readily available. I have a somewhat "leaky" house, and ducts up in the attic as well. I'm working on the sealing many of the cracks and gaps at the floor, at the outlets, and so on, but I'd really hate to have fiberglass leaking out of these gaps. And god forbid it actually somehow got into the ductwork! The roofing is new, there are vents, and I'm working on getting the bath fan to exhaust out the side of the building, not into the attic. There should be no "moisture" in the attic other than ambient humidity! :-)
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yes. see also: http://www.owenscorning.com /
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And figure it is going to settle maybe up to 25% over time
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