On the post-1991 half of this town the rim joist is usually the only significant leak left in the house, and it comes with a relative nobody thinks to mention: the cantilevered floor. They are the same detail in two places, they fail the same way, and on a Coaldale house of that age both of them are reachable without disturbing a finished room.
What the band of framing actually is
Where the floor structure lands on top of the foundation wall there is a band of lumber standing on edge, closing off the end of every joist. That band is a piece of exterior wall, but it is not framed like one. It has no cavity to speak of, it is interrupted every sixteen inches, and it sits exactly where the concrete, the sill plate, the framing and the floor sheathing all meet at once.
Four materials meeting at one line is four chances for a gap, and the batt that was pushed into each bay does nothing about any of them, because insulation does not stop air movement. Air sealing does.
The cantilever at the back of the house
Newer houses here very commonly have a section of floor projecting past the foundation: a dining nook, a bay window, a bumped-out area under a bonus room. The floor joists simply run out over open air and the space under them is closed with soffit material.
That is a rim joist turned sideways and then multiplied, because now there are three exposed faces instead of one and the cold air is underneath as well as beside it. These are the floors people describe as freezing in socks while the rest of the house is fine. What is almost always in there is a batt lying loose in the joist space with a gap above it, so outdoor air circulates between the insulation and the subfloor and the room loses heat to the moving air rather than through the insulation.
Why closed-cell is the right material for both
Closed-cell foam at about R-6 to R-7 per inch adheres to the wood and the concrete, expands into the irregular gap where the sill meets the top of the wall, and at roughly two inches is its own vapour barrier, so no separate poly detail is needed in a space nobody can get back into. Two to three inches in each joist bay seals and insulates in one pass, which is why this is the smallest item we quote and the one owners most often say they noticed.
Two more places with the same shape
On a two-storey house there is a second band of framing at the mid-floor, in the wall between the ground floor ceiling and the upstairs floor. It is less accessible and usually only addressed when the cladding is off.
The other one is the step in the foundation where the house meets the garage. The floor level changes, the framing steps with it, and that step is almost always open to the garage. Sealing it is part of the same visit.
What to check before we come
Look along the top of the basement wall for daylight, for cobwebs that move, and for batts that have fallen out of the bays. Then stand on the cantilevered floor on a cold morning and compare it with the floor two metres away. If you can describe both of those to us on the phone, the visit is quicker and the scope is clearer.
Who quotes it and who sprays it
We are the contractor on rim joist spray foam insulation Coaldale, not a referral service. We quote the job, schedule it and stand behind it, and our own installers carry it out.
Rim Joist Spray Foam Insulation Coaldale: Common Questions
Why is one area of the floor always cold when the rest is fine? That section almost certainly hangs past the foundation. Cold air is below and beside it, and a loose batt in that space does not stop air moving over the subfloor.
There is already insulation in the rim. Is there any point? Yes, because the batt is not sealing anything. The leak is at the joints between the concrete, the sill, the band and the sheathing, and only an adhered material closes those.
Is this worth doing on its own? On the newer stock in this town it is usually the single best value item in the house and it is frequently done as a stand-alone visit.
How much does rim joist spray foam insulation cost in Coaldale? It is priced per board foot over the sprayed area, so the number follows the perimeter length and the number of cantilevered sections. It is the smallest scope on our list and it can often be scoped accurately from a description over the phone.
How do I choose a rim joist spray foam contractor in Coaldale? Ask whether the quote includes the cantilevered floor and the step at the garage, or only the straight run around the basement. Those two are where the complaint usually lives.
Size the job with the R-value calculator, then get a free Coaldale quote. More on Rim Joist Spray Foam Insulation Alberta province-wide.