Basement, Rim Joist & Crawl Space Insulation in Lansing, MI

Basement, rim joist and crawl space insulation targets the bottom of the house, where cold air gets in and warm air gets pulled up and out. The rim joist is the wood band that sits on top of the foundation wall around the whole house. It is thin, often uninsulated, and full of gaps where the sill plate meets the concrete. In a Lansing basement, it is usually the first place we spray.

Why the bottom matters

Warm air rises and leaks out the top of a house. That pulls cold outside air in at the bottom, through the rim joist, sill plate and crawl space. Sealing the bottom slows the whole cycle, so upper floors stay warmer and the furnace cycles less. Floors over unheated crawl spaces benefit most.

Closed-cell foam on rims and walls

We use closed-cell foam on rim joists because it seals the gaps, insulates, and resists moisture in one layer. On poured concrete or block foundation walls, closed-cell foam keeps humid indoor air from reaching the cold masonry, which is where condensation and musty smells start. Michigan's 2015-based code lists R-13 cavity or R-10 continuous for basement walls in Zone 5, and R-19 or R-15 continuous for crawl space walls.

Crawl spaces

Many older homes around Lansing sit partly or fully on crawl spaces, or have a crawl under an addition. Vented crawls with fiberglass hanging from the floor joists are common and rarely work well. We often recommend sealing the vents, insulating the crawl walls with closed-cell foam and adding a ground vapor barrier, so the crawl becomes part of the house instead of a cold, damp box under it.

Finishing a basement

If you plan to frame and drywall the basement, insulate first. Foam on the walls and rim before framing costs less and avoids opening new drywall later. Exposed foam in a basement generally needs a thermal barrier such as drywall, so tell us your finishing plans and we will plan around them.