Rim joist spray foam in Roswell
This is a small job. The rim joist is the short board at the edge of a wood floor, sitting on the foundation. It leaks like crazy, and some houses here do not even have one.
From a basement, a crawl, or a missing soffit, the installer sees a repeating pocket: subfloor on top, band joist on the outside, sill on the foundation, a joist on each side. Old fiberglass comes out. They look for rot and pests. Then closed-cell goes in so it bonds to all three planes. Two or three inches is a common spec, enough to air-seal and slow vapor. Full-bay fill only if the quote says so.
Prep is most of the labor. Access, joist bays stuffed with plumbing, a sill the termites already found: those move the price more than the foam does.
January nights near 23°F plus a leaky rim is cold baseboards and a furnace that short-cycles. April wind then shoves dust through the same gap. People recarpet. The leak is still at the band joist.
Slab houses can ignore this unless an addition was framed over a crawl. Raised floors, older downtown stock, anything with a cellar: look here before you buy an attic package you may still want later.
Closed-cell at the rim does not replace a ground cover in a crawl, and it does not replace flashing at the sill. If the whole box under the house is open, see crawl space spray foam.
Helpful on a request:
- Basement, crawl, or you are not sure
- Whether you can already see the band joist
- Pest damage or damp wood at the sill
- Whether walls or the attic are in the same conversation
I am on a slab. Do I have a rim joist?
A rim (band) joist exists where a wood floor sits on a foundation. A lot of Roswell ranches are slab-on-grade and skip this detail entirely. Additions, converted garages, crawls, and cellars can still have one. Look from a floor hatch or walk the perimeter.
Why not just stuff fiberglass in there?
Fiberglass in a rim bay does not seal the sill, the band joist, or the gap at the subfloor. Closed-cell sticks to those three planes. On a cold January night that is the leak you feel at the baseboard.
Is this a whole-house job?
No. It is a short pass with a lot of leverage. It will not cool a 140°F attic. Some people pair it with crawl or wall work. Some stop here.
Get rim joist foam quotes
Tell us about the attic, crawl space, or building. Licensed local installers follow up. We do not send a crew.