Ever wonder why your floors feel cold even after you've insulated everywhere else? The culprit is probably your rim joist โ the band of framing that sits right on top of your foundation wall. It's exposed to outside air on three sides, and in most older Jonesboro and Trumann homes, it's completely uninsulated.
A typical ranch house has 100โ150 linear feet of rim joist. Uninsulated, that band can account for 15โ20% of total envelope heat loss. With Northeast Arkansas dropping into the 30s overnight through October and staying there until March, that's five-plus months of conditioned air bleeding straight out.
The fix is straightforward: cut-and-cobble rigid foam (R-10 to R-15) sealed at the edges with 2-lb closed-cell spray foam, or simply spray the entire rim joist cavity with 2โ3 inches of closed-cell foam. Three inches of closed-cell hits R-21, which exceeds the IRC R402.1.2 prescriptive requirement for Climate Zone 3 (that's us). Job takes a two-person crew about half a day on a standard house.
Cost typically runs $1.50โ$3.00 per square foot of rim joist area, depending on access and whether the basement or crawl space is already conditioned. On a 1,600 SF ranch, you're looking at roughly $300โ$600 total โ often the cheapest energy upgrade per dollar spent on an older home.
If your heating bill spiked last winter or your baseboards never quite keep up in January, a rim joist inspection should be your first call. Reply or DM us for a free estimate โ we serve Jonesboro, Trumann, Paragould, and surrounding areas.