Do-It-Yourself Blow-In Attic Insulation

Install cellulose insulation with special blowing equipment, which must be rented. It has a hopper to hold insulation, a blower to push it out and a hose to direct it into place. Put cellulose over any existing dry insulation if that is in good shape, not damp or deteriorated. Remove any defective existing insulation and check the space for signs of leaks or other problems before starting.

Figure the amount of insulation needed. Mentally divide the attic space into quadrants, then calculate the insulation needed for one quadrant. A bag of dry insulation may cover about 40 square feet to a depth of about 7 inches (an R value of 26). A 30-by-30-foot attic will have 900 square feet or 225 per quadrant; 40 square feet per bag would require about 5 1/2 bags per quadrant.

Remove any objects that would interfere with insulation and put up baffles to prevent soffits or vents from being covered up. Load the blowing machine with insulation. Start at the far wall, holding the blowing machine hose parallel to the floor and letting the insulation fall 10 to 12 inches away. Blow insulation in the direction of the floor joists. Fill to the tops of wall cavities.

Fill 3 or 4 joist cavities, then move over and repeat the process. Move to the other end of the attic after one half is done. Work toward the opening where you will exit the attic, so the final cavity will be right at that spot. Keep the hose close to the floor to go under obstructions or electrical wires. Check the depth to make sure it is proper and fill any low spots before exiting.