How to Estimate Blown-In Insulation
- 1). Measure the width and and length of your attic space with a measuring tape.
- 2). Determine the amount of depth of insulation you would like to add to the attic and the specific R-value-per-inch of your chosen insulation type. If the target is to add R30 to the attic and the insulation chosen has a R-value-per-inch of five, you need a depth of 6 inches (30 / 5 = 6 inches). The amount of total insulation you need in your attic varies due to your local climate. Refer to the Resource section for a zip code calculator that determines the ideal R-value for your local area.
- 3). Multiply the attic's width x length x insulation depth to determine the volume (in cubic feet) needed to fill the area in the attic.
- 4). Calculate the number of insulation bags needed to cover the attic. Go to the store and look on the insulation package for its maximum coverage per bag in cubic feet. Divide the total attic area from Step 3 by the per bag coverage. The result is the number of bags you need to buy.
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