How Can I Add Insulation Behind My Existing Drywall?

With the high cost of heating and cooling your home, it pays to ensure that your walls are well insulated and energy efficient. Unfortunately, older homes and poorly constructed homes may have inadequate insulation in the walls. In addition, some older types of insulation settle and compress with age, leaving gaps in the walls that reduce your homes thermal resistance, or R-value. The best time to insulate the walls is before the drywall is in place, but you can still add insulation to existing walls later if you need additional insulation.

Insulation Options

You have a couple of choices for insulating existing walls. The first is to remove the drywall and install new insulation bats in the stud spaces before installing new drywall panels and taping them out. Unfortunately, that’s not always feasible for homeowners who are living in the home. The other option is to blow in fiber or cellulose insulation behind the existing drywall. A contractor usually performs this task, and you may continue living in the home.

The Process

In order to add insulation behind existing drywall, the contractor must gain access to every stud space on the exterior wall. The contractor drills one or two holes on the exterior of the home at the top of each stud space and blows cellulose fibers into the space. The fibers filter downward and fill the space, adding insulating value. After he’s done, the contractor will plug the holes to match the exterior siding on your home. If your home has masonry siding, your contractor may blow in the insulation from inside the home.

Considerations

Although blowing insulation into stud spaces adds to your home’s energy efficiency, it’s not a perfect solution. As the insulation filters downward, wiring, gas lines and outlet boxes can block the insulation, creating voids and gaps that reduce the wall’s overall R-value. 

Additional Solutions

New energy efficient replacement windows, or storm windows, can reduce heat transfer through exterior walls. Re-siding an older home with foam-backed siding is another option. Even small steps, like adding new weather stripping to doors and caulking gaps between in exterior siding will reduce drafts and increase energy efficiency.