Wall Insulation in Asheville, NC

Wall insulation is often missing from older Asheville houses. Homes from the city's 1910s and 1920s building boom, and many from the decades after, were framed with empty stud cavities. Rooms with exterior walls on two or three sides feel cold in winter and warm in summer, no matter what the thermostat says. There are two ways to fix that, depending on whether the walls are open or closed.

Closed walls: dense-pack

For finished walls, we drill small holes from inside or outside, fill each stud bay with cellulose packed tightly enough that it will not settle, then plug and patch. Dense-pack slows air movement within the cavity as well as insulating. On plaster walls, the holes are usually made from the outside under a course of siding, then the siding goes back. HomeGuide lists dense-pack cellulose at $1.60 to $4.20 per square foot.

Open walls: spray foam

During a remodel, an addition or new construction, the studs are exposed and spray foam is the stronger choice. Open-cell fills the cavity and seals air at a lower cost. Closed-cell reaches a higher R-value in the same depth and adds a vapor retarder, which can matter on walls next to a damp hillside or on below-grade walls in a walk-out basement. Fixr lists new construction foam at $2.75 to $6.50 per square foot.

Before we fill a wall

We check for knob-and-tube wiring, which should be evaluated by an electrician before insulation goes around it. We check for signs of water getting into the wall, since insulation will hold moisture against siding and sheathing. We look at blocking inside the walls, which can leave empty pockets if not found. And we check that bath and kitchen fans vent outside.

What to expect

A closed-wall job usually takes one to three days for a typical house. Interior work involves some dust; exterior drilling involves removing and replacing siding pieces. We tell you up front which approach we plan and what patching is included.