Ever wonder why your floors feel cold in November even with a heated crawl space? The culprit is usually the rim joist โ that narrow band of framing where your floor system meets the foundation wall. It's one of the most overlooked thermal weak spots in a Northeast Arkansas home.
A typical uninsulated rim joist has an effective R-value close to R-3. IRC Section R402.1.2 (Climate Zone 3, which covers Jonesboro and Trumann) calls for R-15 in that cavity. That's a massive gap, and your heating system is making up the difference every single month.
The fix is surprisingly clean. Two inches of closed-cell spray foam applied directly to the rim joist band delivers roughly R-14 to R-15 โ meeting code in a single pass. Closed cell wins here because it also acts as an air and vapor barrier, stopping the moisture that rots rim joists over time. Cost runs $2.50โ$4.00 per board foot installed, and a typical 1,500 SF footprint might use 150โ200 board feet of material.
Most rim joist jobs in this area are finished in half a day. Homeowners routinely report noticeably warmer floors by the first cold snap โ usually mid-October here in the Arkansas Delta. Pair it with a crawl space vapor barrier and you've addressed two of the top three sources of winter heat loss in one visit.
If you're already planning crawl space work or an attic top-up before the weather turns, bundling the rim joist into the same appointment almost always saves on mobilization cost.
Reply to this post or DM us for a free rim joist estimate โ we serve Jonesboro, Trumann, Paragould, and surrounding communities.