On a house built in the last fifty years the rim joist is a tidy detail: a board on edge closing the ends of the floor joists, sitting on a sill plate on a poured wall. Rim joist spray foam insulation in Fort Macleod frequently involves something else entirely, because about 81% of homes here predate 1991 and a good number of them predate the detail.
There may not be a rim joist up there
Go into an old cellar with a light and look at the top of the wall. On a fieldstone or rubble foundation you will often find the joists bearing directly into pockets left in the stonework, with no continuous band closing them off. Each joist end sits in its own hole in the wall. In a balloon-framed house the studs run past the floor, and instead of a band there is a gap beside every stud, open from the cellar to the roof.
Those are three different conditions wanting three different approaches, and which one you have cannot be guessed from the age of the house. It has to be seen.
Look before you seal, and mean it
This is the part worth being blunt about. A timber joist end bearing in a stone or brick wall is in the dampest, least ventilated spot in the building. Some of them are perfectly sound. Some have been slowly rotting for decades and are being held up mostly by habit.
Spraying closed-cell foam over a wet or soft joist end does two unhelpful things. It seals it away from the only drying it was getting, and it hides it from anybody who might otherwise have noticed. So on this stock the first pass is an awl and a flashlight on every accessible pocket, not a hose. If something is soft, that gets fixed before it gets covered.
That caution is specific to old masonry pockets. A sound sill on a poured wall needs none of it.
Why this spot is still the best value in the house
Once it is proven sound, nothing in an old house returns as much for as little. The band is the junction of three assemblies — foundation, floor, wall — and junctions leak. It is uninsulated in nearly every house of this age, or it has a scrap of batt pushed into each bay that air passes straight through. It is cold, it is low in the house, and it is where the air comes in that leaves through the ceiling later.
It is also accessible. No finishes come off, nobody moves out, and the work is done from the cellar in a day on most houses. Closed-cell foam at the band seals and insulates in one pass and follows the irregular shapes that old framing produces.
Do the top of the house in the same visit
Air entering low leaves high, and the pair is one system. Sealing the band without sealing the ceiling plane changes the pressure pattern more than the total. The highest-value version of this job is the band plus the vertical shafts — the abandoned chimney chase, the old flue openings, the stack, the gaps at the top of the partitions.
If a household can only do one thing, this is the one. If they can do two, this plus the ceiling plane. We quote the job, schedule it and stand behind it.
What a household notices afterwards
Floors over the cellar that are less cold underfoot. Rooms at the corners of the house that stop being the ones nobody sits in. A furnace that cycles less in the evening. It is not a dramatic change in a single number, and on an old house it is usually the most noticeable improvement per dollar anybody makes.
Rim Joist Spray Foam Insulation Fort Macleod: Common Questions
What if our joists just sit in the stone wall? Then each pocket is its own detail and each one gets looked at before anything is sprayed. It is still worth doing, but inspection comes first.
Why inspect before sealing? Because a damp joist end bearing in masonry can be rotten, and foam over it removes both the drying and the chance of noticing.
Is this really better value than the attic? On this stock, generally yes as a first job, and the two together are better than either alone.
How much does rim joist spray foam insulation cost in Fort Macleod? It is priced per board foot over the sprayed band area, so the number follows the perimeter and the thickness. Repairs found during the inspection are separate and quoted once they are seen.
How do I choose a rim joist spray foam contractor in Fort Macleod? Ask whether they check the joist ends before spraying on a stone foundation. On a house of this age that answer matters more than the price.
Size the assembly with the R-value calculator, then get a free Fort Macleod quote. More on Rim Joist Spray Foam Insulation Alberta province-wide.