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How to calculate how much cellulose for a dense-packed wall?

For the life of me I can't figure out how to calculate how much blown in cellulose we will need for the walls. 2X6 2ft on center with 8 ft ceilings. Applying Insulweb and dense packing.
I hear 3.5lbs per cubic feet
If I just knew how much one cavity would take I could get it figured.
How do is this calculated?

Asked by Gabriel Gonzales
Posted Oct 19, 2013 10:16 PM ET
Edited Oct 20, 2013 8:06 AM ET

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1.

Gabriel,
To calculate volume, you multiply width by depth by height.
A typical 2x6 stud cavity might measure 14.5 inches by 5.5 inches by 92 inches.
Multiply the three numbers together, and you get 7,337 cubic inches.
Since 1,728 cubic inches equals 1 cubic foot, we divide by 1,728 to get cubic feet, so:
7,337 cubic inches = 4.2 cubic feet
So, to fill a stud cavity of this size, you'll need 4.2 cubic feet of cellulose. If you are installing the cellulose at a density of 3.5 pounds per cubic feet, you multiply the number of cubic feet by 3.5 to determine how many pounds of cellulose you need.
That means that you need 14.7 pounds of cellulose to fill a cavity measuring 4.2 cubic feet.

Answered by Martin Holladay, GBA Advisor
Posted Oct 20, 2013 6:13 AM ET

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