Rim joist insulation

Why rim joists matter

Look along the top of your basement wall and you'll see the end of every floor joist sitting on the foundation, boxed in by the rim board. Each of those pockets has seams: where the subfloor meets the rim board, and where the framing sits on the sill plate.

Those seams let outside air in. Batts stuffed into the pockets slow heat loss but don't stop air moving through the gaps.

What spray foam does here

Closed-cell spray foam is sprayed into each pocket. It expands into the seams, bonds to the wood and concrete, and cures into one continuous layer that both seals and insulates.

• Works in finished and unfinished basements, as long as we can reach the joist pockets
• Often the first job people do, because it's a small area with a noticeable result
• We'll tell you at the site visit what needs to be cleared or opened up