In a town where most houses predate 1991, the rim joist is often the only piece of original construction a homeowner can still see. Everything else has been covered, re-sided, re-roofed or drywalled over. The band where the floor framing sits on the foundation is still exactly as it was built, which makes rim joist spray foam insulation in Innisfail an unusually honest piece of work: you can look at the problem before you fix it.
Where the band sits in a frozen landscape
Frost goes deep here and stays down for months. The foundation wall below grade is in contact with that frozen soil but is shielded by the earth above it, so it loses heat slowly. The band joist is in a different position entirely. It sits above the foundation, in open air, with nothing but the siding and a thin strip of sheathing between it and an outdoor temperature that can hold well below freezing for weeks. It is the coldest part of the heated envelope and it is also the part with the most joints in it per square metre.
Why a small area leaks so much
Count what meets at that band. The top of the foundation wall. The sill plate, usually sitting on nothing more than a strip of material that has compressed over the decades. The end of every floor joist, each one a separate bay with its own pair of corners. The subfloor above. The sheathing outside. In an older house there is also whatever has been drilled through it since: the gas line, the electrical service, the hose bib, a dryer vent, and in some cases a telephone line nobody has used in twenty years. Each of those is a hole with the house's warm air going out of it.
Cold air comes in low and stays low
Air leaking in at the rim does not mix. It is dense, so it spreads across the basement floor and stays there, which is why a basement can have a cold floor and a comfortable ceiling at the same time. It also feeds the stack effect, because every litre entering at the bottom replaces a litre leaving at the top. Closing the band therefore does two things: it stops the cold draught at floor level and it reduces the rate at which the whole house exchanges air through its other leaks.
What is actually in the bays now
In this vintage of house, usually a batt pushed into each bay with a vapour barrier facing the wrong way, or nothing at all. The batt does not seal, so air still moves around it, and because the rim behind it stays cold the moisture in that air condenses on the wood. Pull one out and you often find staining on the joist end and a dark mark on the sill. Closed-cell foam sprayed into the bay adheres to the rim, the sill, the subfloor and the joist sides in one operation, and at roughly two inches it is a vapour barrier itself, so there is no air against cold wood to condense.
A job that fits in part of a day
This is the smallest worthwhile scope in a house and often the most noticeable. The bays are reached from inside the basement, nothing has to be opened up, nobody has to move out, and the work is done in a part of the house that is usually unfinished anyway. On a house with a finished basement the bays are frequently still accessible above a dropped ceiling or behind a removable section, which is worth checking before assuming the job is off the table.
We take care of the work
We do rim joist spray foam insulation Innisfail ourselves. We scope and quote it, we book it, and our own installers spray it -- one company, one point of contact.
Rim Joist Spray Foam Insulation Innisfail: Common Questions
Why is the rim joist colder than the basement wall? Because it sits above the foundation in open air. The wall below grade is shielded by the ground; the band is not shielded by anything.
The basement floor is cold but the room is not. Why? Cold air entering at the band is dense and spreads across the floor rather than mixing with the room air above it.
Do the old batts come out? Yes. They have to come out for the foam to bond to the rim, and they are usually damp and stained on the back face anyway.
How much does rim joist spray foam insulation cost in Innisfail? It is priced per board foot of sprayed area at the specified thickness, so the number follows the perimeter of the house and the joist depth. It is a small quantity of material and a lot of detail, which is why it is quoted by the band rather than as part of a wall price.
How do I choose a rim joist spray foam contractor in Innisfail? Ask whether they will do every bay including behind the furnace and the service entry, or only the accessible runs. The awkward bays are where the leaks are.
Size the band with the R-value calculator, then get a free Innisfail quote. More on Rim Joist Spray Foam Insulation Alberta province-wide.