Basement & Rim Joist Insulation in Appleton, WI

Basement and rim joist insulation fixes one of the leakiest parts of a Fox Cities house. The rim joist is the band of lumber that sits on the sill plate on top of the foundation, and in most homes it is either bare or has a batt pushed against it. Air comes in at the sill, around joist ends and through holes for pipes, wires and dryer vents. That cold air drops across the basement floor and is a big reason floors above feel cold.

Why we use closed-cell foam

A batt against a cold rim lets warm, humid air through to the wood, where it can condense in winter. Closed-cell foam bonds to the wood and leaves no gap for moist air to reach. At R-5 to R-7 per inch by HomeGuide's rating, a few inches gives solid R-value in a small space, and it seals every pipe and wire hole at the same time.

Foundation walls

Wisconsin's code summary lists R-19 cavity or R-15 continuous insulation for basement walls in Zone 6. If you are finishing the basement, the walls should be insulated before the framing goes in. Closed-cell foam or rigid board against the concrete keeps warm air off the cold wall, and the stud wall is built in front of it. We look for seepage, cracks and white mineral deposits first, because those need attention before anything covers them.

Crawl spaces and floors over garages

Some homes have a crawl space under an addition or a sunroom. We insulate and seal the walls, lay a vapor barrier over the soil and seal any vents. Floors over attached garages get foam in the joist bays, which also blocks fumes.