Ever wonder why your floors feel cold even after upgrading your attic insulation? The culprit is often the rim joist โ that band of framing sitting right on top of your foundation wall. It's one of the most overlooked air leaks in Northeast Arkansas homes, and it's working against you hard right now as we shift from brutal August heat into the swing season.
A typical uninsulated rim joist leaks air like a screen door. We're talking dozens of small gaps where the sill plate, band joist, and floor decking all meet โ each one letting conditioned air escape and outside air sneak in. In a standard 1,500 SF ranch home, the total rim joist area usually runs 100โ150 SF, and every square foot of it is exposed to outside temps.
The fix we use almost every time: two-component closed-cell spray foam, applied at 2 inches thick. That gets you to R-13 in a tight, air-sealed layer โ meeting IRC R402.2.1 requirements for wood-framed floors in Climate Zone 3 (that's us). Closed-cell is the right call here because it also acts as a vapor retarder, which matters in a damp Arkansas basement or crawl space. Installed cost typically runs $4โ$6 per board foot, and a full rim joist job on a mid-size house can be done in a single morning.
Most homeowners who get it done tell us they notice the difference in floor comfort within days โ and see it confirmed when the next utility bill lands. It's a small job with outsized impact, which is exactly why we love it.
Reply or DM us for a free rim joist estimate โ we serve Jonesboro, Trumann, and all of Northeast Arkansas.