How to Retrofit Cavity Wall Insulation
- 1). Locate and mark each stud for the wall you're insulating with a stud finder, marking the locations of each one at the top of the wall.
- 2). Load your drill with your hole-saw bit. Cut a hole at roughly the center point between each pair of studs, about eight inches down from the ceiling. Save the circular cutout pieces.
- 3). Set up your insulation blower with loose cellulose insulation. Put the end of the blower hose into one hole. Push the hose down as far as it will go. Stuff rags around the edge of the hole, where it enters the wall, to get a tight seal.
- 4). Turn on the blower. Let the insulation flow out into the wall cavity, while slowly pulling the hose upward. You will be able to hear the motor of the blower strain when insulation is piling up around it, indicating you need to pull it up higher. Continue until the end of the hose is about to come back out of the hole. Turn off the machine just before you pull it out completely.
- 5). Repeat the process for each hole.
- 6). Plug each hole with a circular cutout piece of wall, that you saved earlier. Press mesh drywall tape over each cutout areas. Spread patching plaster over each hole with a drywall knife, getting it smooth and flat. Let it dry for six to eight hours, then lay a second layer of plaster over it. Repeat for a third layer, sand the area smooth, and repaint.
