How to Install Fiberglass Attic Insulation
- 1). Measure how much insulation you will need. Multiply the square footage of your attic by .90 if your joists are 16 inches apart and .94 if they are 24 inches apart. For example, if your attic is 1,000 square feet and you have 16-inch joists, you will need 900 square feet of insulation.
- 2). Lay out sheets of plywood to kneel or stand on so you don't step through the ceiling below.
- 3). Install the fiberglass batting with the vapor barrier face down. Lay them out in sections, starting on one side of your attic and working toward the center so you will have more headroom at the end of the project when you are cutting and pieces smaller sections of fiberglass.
- 4). Place the fiberglass batting end-to-end, fitting them tightly together. Lay the insulation over and across the top plate of the exterior walls, but don't block the eave vents. Cut scraps of fiberglass to fill any small spaces.
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