Wall Insulation in Des Moines, IA

Wall insulation depends on one question: are the walls open or closed? In an addition, a gutted remodel, a garage conversion or a new build, the studs are exposed and spray foam can fill each bay. In a finished Des Moines house with plaster or drywall that is staying, the walls are filled from small holes with dense-pack cellulose or fiberglass. We do both, and we start by finding out what is in your walls now.

The code number

Iowa's Table R402.1.1 lists R-20, or R-13 in the cavity plus R-5 continuous, for wood-frame walls in Climate Zone 5. In a 2x6 wall, open-cell foam or batts can reach R-20. In a 2x4 wall, there is only about three and a half inches of space, and closed-cell foam at R-5 to R-7 per inch (HomeGuide) is one of the few ways to get close. That is why we often recommend closed-cell for additions framed with 2x4s and for walls between the house and an attached garage.

New construction and additions

The metro's newer suburbs are still building: Point2Homes data shows 38.1% of Waukee homes built from 2010 to 2019 and 40.2% of Grimes homes in the same decade. Iowa's code requires new homes to pass a blower door test at 4 air changes per hour or less, and foam in the walls and at the rim helps a house get there. We coordinate with your builder so foam goes in after rough-in inspections and before drywall.

Older houses with empty walls

Many pre-war Des Moines houses were built with no wall insulation at all, and some of the walls are open at the top and bottom so air moves through them freely. We check by removing an outlet cover or drilling a small test hole. If the cavities are empty, dense-pack cellulose blown at high density fills them and slows air movement. On older siding, the holes can often be drilled from outside under a lifted course; on plaster, from inside, then patched. Expanding foam is rarely the right choice for closed walls.

Garage and shared walls

Rooms over a garage and walls shared with an attached garage are common complaints in suburban homes. We seal the garage ceiling and the rim between the garage and the house, and insulate the shared wall to the house-side standard.

Sound between rooms

Open-cell foam and dense-pack both cut sound through interior walls and floors, which helps around home offices, bedrooms next to living rooms and basement media rooms. Get a free estimate