The rim joist is the band of framing at the top of the foundation where the floor meets the wall, and on most houses there is one of them. On a Raymond house there are usually several. Rim joist spray foam insulation in Raymond has to deal with that, because each addition built out across the wide lot sat on its own foundation at its own depth, with its own floor level and its own band of framing, and the ones added later are often not facing outdoors at all.
More than one rim joist, at more than one height
Picture the house in section. The original core has a rim joist at the top of the basement wall. The addition off the back sits lower, on a shallow foundation, so its rim joist is a foot or two below the first one and runs around a different perimeter. A third room sits on piers, so its floor is framed on beams with a band board around the outside and nothing underneath but outdoor air. Now the part that catches people: where the addition meets the original house, the original rim joist no longer faces the weather. It faces into the crawl space under the addition. It is still a rim joist, it still leaks, and because it looks like an interior detail nobody treats it.
Why this band leaks more than anything else per square foot
There is a lot going on in a few inches. The floor joists land on the sill, so the band is interrupted every sixteen inches by the end of a joist, creating a pocket at each one. The sill sits on concrete or block, which is never perfectly flat, so there is a joint along the whole length. The sheathing above and the foundation below meet here. Services pass through: the water line, the gas line, the electrical service, the dryer vent, old telephone and cable entries, hose bib supplies. Each of those is a hole through the band. Add them together along the whole perimeter of three separate structures and you have more opening than any window in the house.
Why foam suits this particular space
Each joist pocket is a small, irregular, three-sided box with a joist end in it, and it is different from the one next to it. A batt pushed into it touches on two sides and leaves air paths at the top, the bottom and around the joist. Rigid board has to be cut for every pocket and sealed at every edge, which can be done well and almost never is. Closed-cell foam is sprayed into the pocket, expands into the corners, adheres to the band, the sill and the joist end at once, and at roughly two inches is its own vapour control, which matters because this is a location where warm humid indoor air meets the coldest framing in the house. It is one of the few places where the product choice is not really arguable.
Do the one facing the crawl space too
Worth repeating because it is the local detail. If you seal only the rim joists on the outside walls, the one between the basement and the crawl space under the addition is left open, and that is the one connecting two spaces at very different temperatures. The duct run to the far end of the house passes through there. Sealing the outdoor-facing bands and skipping the interior one is a half job that feels like a whole one.
Look before sealing
We check for a few things before spraying: active water staining, which means a drainage problem that comes first; soft or insect-damaged sill, which has to be dealt with rather than covered; knob-and-tube or other old wiring in the band, which cannot be buried in foam; and any combustion appliance drawing air from the basement, because sealing changes where it gets that air. None of these are common enough to worry about and all of them are cheaper to find before the hose comes out.
And do the top of the house in the same project
The rim joist is the bottom of a pressure difference and the attic is the top of it. Sealing only the bottom reduces the leak but leaves the engine running. The two together are what produce the change people notice in a cold back bedroom.
We take care of the work
On rim joist spray foam insulation Raymond, the people who quote the work are the people who do it. We insulate it ourselves and we answer for the result.
Rim Joist Spray Foam Insulation Raymond: Common Questions
How can a house have three rim joists? Because it was built in three stages on three foundations at three levels. Each stage has its own band of framing around its own perimeter.
Why is one of them inside the house? Because the addition was built against it. It now faces into the crawl space under the addition instead of outdoors, and it still leaks.
Is this a job on its own, or part of something bigger? It is a legitimate standalone job and it is one of the highest value ones. Pairing it with attic sealing gets you more again.
How much does rim joist spray foam insulation cost in Raymond? Priced by sprayed area, which here means linear perimeter by band height, so the number scales with how many separate perimeters your house has.
How do I choose a rim joist spray foam contractor in Raymond? Ask how many rim joists your house has and whether the one facing the crawl space is in the quote. That single question tells you a lot.
Size the assembly with the R-value calculator, then get a free Raymond quote. More on Rim Joist Spray Foam Insulation Alberta province-wide.