How to Blow Insulation in Walls

While most people recognize the importance of insulating attic spaces, many do not realize the need to insulate walls. Exterior walls should be insulated to help keep energy costs down. Insulation also reduces noise. Batt insulation, which is pre-cut panels of insulation, is often used for new construction because the wall cavities are easily accessible. For existing homes, blown insulation is preferred and is usually completed by a professional.

Difficulty: Moderately Challenging

Instructions

Things You'll Need:

• Hole saw Drill Blow machine Plugs

1. Decide whether to blow insulation in from the interior or exterior of the home. Generally, professionals choose to blow from the outside, thereby reducing repair to interior walls.

2. Remove one section of siding along the side of the home at each floor. At window openings, remove a piece above and below the window to access the wall cavity. If the home is brick or stucco, perform the operations from the interior, drilling through drywall or paneling.

3. Drill a 2-inch hole to access the wall cavity. The cavities run vertically along the house, each between the frame studs. Only one hole is needed for each floor if there is no window or door opening separating the cavity. Measure along the length of the wall to locate where to drill your holes. Begin at the corner of the home, keeping in mind that the studs should be on 16-inch centers.

4. Insert the hose from the blow machine into the cavity and blow in insulation. The blow machine should have a pressure gauge to indicate when the cavity is full. The pressure rating varies from machine to machine.

5. Reinstall siding after all cavities have been filled. Patch holes in the interior drywall or paneling if the insulation was blown in that way.

Tips & Warnings

• If you do not have vinyl siding, drill through the exterior finish of the home. Plugs are available to seal the holes. The plugs can be painted. To insulate cavities from the interior, remove all the drywall or interior wall finish. This creates a great deal more work but gives you the option of using batt insulation as in new construction. Blow machines are fairly expensive and not normally rented to the general public. Wall insulation is best left to professionals.
• If the drywall is not installed properly, or if too much insulation is put in, it can cause the drywall to pop and allow insulation to blow into the interior of the home.

References

• U.S. Department of Energy: Wall Insulation