Wall Insulation in Montgomery, AL

Wall insulation is the next step after the attic and crawl space in many Montgomery homes, and the right method depends on whether the walls are open. Plenty of older houses in the city were built before insulation was routine, and the wall cavities are empty or have only paper-faced batts that have slumped over the years. Newer homes built to code have insulation in the walls, but the gaps around outlets, windows and top plates still leak.

Open walls: additions, remodels and new construction

When the studs are exposed, spray foam fills the cavity completely and seals the joints between framing members, sheathing and rough openings. Fixr lists new construction spray foam at $2.75 to $6.50 per square foot. Open-cell foam is common in exterior walls here because it fills well and costs less; closed-cell adds strength and a vapor retarder where that helps, such as walls next to a garage or a damp lower level. Alabama's amended code lists R-13 for wood-frame walls in Zone 3; in a 2x4 wall, closed-cell foam reaches that with room to spare, while a full cavity of open-cell lands close to it, so we talk through the numbers before you choose.

Closed walls: older homes

For finished walls in an older house, opening every wall to spray foam rarely makes sense. Dense-pack cellulose or fiberglass blown through small holes, from inside or outside, fills the cavity and slows air movement. HomeGuide lists dense-pack cellulose at $1.60 to $4.20 per square foot and blown-in exterior walls at $1,900 to $7,800. Some contractors offer injection foam for closed walls, and Fixr puts foam in existing walls at $3.15 to $7.50 per square foot.

What we check first

Before filling a closed wall, we confirm the cavities are actually empty and look for knob-and-tube wiring, which should be dealt with by an electrician before any insulation surrounds it. We also check the outside of the house for siding or flashing problems that let water into the walls, since insulation should not trap a leak.