How to Install Blown Side Wall Cellulose Insulation

Old houses are often drafty because they weren’t insulated properly when they were built, if insulated at all. If you’re remodeling your home and the walls are torn open, then you can easily insulate those walls with fiberglass strips. However, if your walls are closed, it gets more complicated. One method available in homes with horizontal slat siding is to blow in loose insulation from outside, taking off one course of siding to access the wall.

Hammer
Pry bar
Electronic stud finder
Pencil
Insulation blower
Cellulose insulation
Jigsaw with heavy wood-cutting blade
Foam insulation (in a spray can)
Cement trowel
Siding nails

Instructions

- 1
  Remove one horizontal strip of the exterior siding from the house using a prybar and hammer, at a height just below the interior ceiling of the room you are insulating. Don’t break the siding as you take it off. Set it aside.
- 2
  Find and mark the position of each stud in the wall, using your electronic stud finder and a pencil.
- 3
  Hold the open mouth of the insulation blower against the wall halfway between each pair of studs, as marked by your pencil. Trace around the mouth of the blower hose and onto the exposed sheathing, making a circle slightly wider than the hose.
- 4
  Repeat, drawing a circle between each pair of studs. Cut out each circle with a jigsaw. You may have to drill a hole to get the jigsaw blade started.
- 5
  Load the insulation blower with cellulose insulation. Feed the blower hose into the first hole, pushing it all the way in, so the end of the hose is at the bottom of the wall cavity inside.
- 6
  Turn on the machine and fill the space between the first set of studs with cellulose. Withdraw the hose slowly as the cavity is filled. Repeat the process to fill each cavity between each pair of studs.
- 7
  Cap each hole with spray foam insulation. Use your cement trowel to flatten the foam insulation on the wall. Let it dry completely.
- 8
  Use your hammer and siding nails to reinstall the strip of siding over the sealed holes.

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