Wall Insulation for Older Homes in St. Paul, MN

Wall insulation for older homes is a big part of insulation work in St. Paul, where census estimates show 41.6% of homes were built in 1939 or earlier. Many houses from that era have plaster walls with nothing in the stud cavities except air. Cold walls make rooms feel drafty even when the thermostat says 68, and air moves freely through the empty bays from the basement up to the attic.

Dense-pack from outside or inside

The usual fix for a closed wall is dense-pack cellulose or fiberglass. We drill a row of holes in each stud bay, either from the outside after lifting or removing a course of siding, or from the inside through the plaster. A hose goes in and fills the cavity tight enough that it will not settle. Holes are plugged and patched, and siding goes back. Dense-packed cellulose also slows air movement through the wall, which loose batts do not.

Check before we drill

We look for knob-and-tube wiring first. Live knob-and-tube should not be buried in insulation, so it needs an electrician's review before we fill. We also find fire blocking, window headers and other obstructions so every part of the bay gets filled, and we check the outside for siding that is trapping moisture.

Open walls are a different job

If the walls are open during a remodel, addition or basement finish, we can spray closed-cell foam, open-cell foam with a vapor retarder, or install other insulation to the code values for Climate Zone 6. The efficientwindows.org summary of Minnesota's 2012 IECC-based code lists R-20 plus R-5 continuous, or R-13 plus R-10, for new wood-frame walls in that zone.

Rebate for empty walls

Xcel Energy's 2024-2026 Minnesota rebate summary pays 40% of cost, up to $1,200, for wall insulation when the cavities were empty before and reach R-11 or better after, and it requires air sealing on the same project. Eligibility depends on your heating fuel supplier, so check before you start.

Call (651) 661-2833 or ask for a quote. Get a free estimate