Ever wonder why your floors feel cold even after you've insulated the attic? The culprit is probably your rim joist โ and it's one of the most overlooked gaps in Northeast Arkansas homes heading into fall.
The rim joist is the band of framing that sits right on top of your foundation wall, where the floor system meets the exterior. In an uninsulated home, this zone is essentially a row of open holes to the outside. Studies show rim joists can account for 10โ15% of a home's total heat loss โ and with Jonesboro winters regularly dipping into the mid-20sยฐF, that adds up fast on your Entergy bill.
The fix is straightforward. We cut 2-inch closed-cell spray foam boards or spray 2โ3 inches of closed-cell foam directly into each joist bay. Two inches of closed-cell hits R-13, and three inches gets you to R-19 โ both solid performers for Climate Zone 3 (Northeast Arkansas). IRC R402.1.2 actually requires R-15 for this assembly in new construction, so if your home was built before 2012, there's a good chance yours is code-deficient right now.
Cost-wise, a typical Trumann or Jonesboro home has 100โ160 linear feet of rim joist. Spraying it out runs roughly $3.50โ$5.00 per board foot installed โ most jobs land in the $400โ$900 range total. That's often a 2โ4 year payback through energy savings alone, before you even count the comfort upgrade and the moisture barrier closed-cell foam adds against that Arkansas humidity.
If you're scheduling any crawl space or basement work this fall, add the rim joist to the scope. It's a small line item with a big return.
Reply or DM us for a free rim joist estimate before the weather turns โ slots are filling up for October.