How to Insulate a Garage That Is Already Drywalled

If you want to insulate a garage that's finished with drywall, you don't have to rip open the walls. One alternative is to blow in loose insulation through holes in the walls, sealing up each space between the studs. The easiest way to do this is from the exterior, which you can do if you have horizontal siding that you can partly remove and reinstall.

Step ladder
Prybar
Hammer
Electronic stud-finder
Pencil
Rented insulation blower
Jigsaw
Cellulose insulation
Foam insulation (in a spray can)
Drywall knife
Siding nails

Instructions

- 1
  Use your hammer and prybar to remove a course of the garage siding, near the top of the exterior wall. Don’t break the siding as you remove it. Set it aside.
- 2
  Locate each stud in the exterior wall using an electronic stud-finder. Use your pencil to mark the halfway point between each stud space, marking on the exposed sheathing where you removed the siding.
- 3
  Press the mouth your blower hose to the wall over the first mark. Trace a circle around it and then expand this circle by a quarter of an inch. Repeat for each mark. Use you jigsaw to cut out each of the traced circles.
- 4
  Fill the insulation blower with cellulose insulation. Thread the blower hose into the first hole, all the way to the bottom of the wall between the first two studs.
- 5
  Turn on the blower and fill the cavity inside with loose insulation. Withdraw the hose slowly as it fills. Repeat for each hole.
- 6
  Plug each hole with spray foam insulation. Smooth out the foam insulation with a drywall knife. Let it dry to the touch, about an hour.
- 7
  Re-install the strip of siding that you removed, using your hammer and siding nails. Repeat the whole process for each wall of the garage.

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