The rim joist is the band of framing that sits on the top of the foundation and carries the ends of the floor joists, all the way round the house. On the roughly three in four Barrhead homes built before 1991 it is visible from the basement at about head height, it has a scrap of batt pushed into each bay, and nothing seals it to anything. Rim joist spray foam insulation in Barrhead is the smallest job on the list and the one we recommend first more often than any other.
Why so little is working up there now
Look at a bay. There is a piece of fibreglass wedged in, held by friction, not touching the wood on at least two sides. Behind it is the rim board itself, with outdoor air on the far face and a joint at the top of the concrete that was never sealed. Air comes in at that joint, moves freely around the batt, cools the wood, and carries on into the floor cavity above, which on a lot of these houses is open into the exterior wall at the ends of the joists.
The batt is not even slowing it down. It is a filter in an air path. And because the wood behind it stays cold while the house air is warm and humid, the batt is also the place where water is collecting — which is why the one somebody pulls out is often damp at the back and the bottom plate under it has gone dark.
A sprayed layer in the same bay behaves completely differently, because it bonds to the rim board, the joist sides and the top of the foundation at once. At about two inches of closed-cell it is also doing the vapour control, so the dew point sits in the plastic and not on the lumber. There is no gap left for air to work in and nothing to fall out.
The bays that cause the trouble around here
Three of them, repeatedly.
The band under the back entry addition. Where a porch or boot room was added, its floor framing was tied into the original house in whatever way worked on the day, and the junction between the two rims is never a clean line. It is usually the single leakiest spot on a Barrhead house, and it is immediately below the door everybody uses.
The bays behind a deck ledger. The deck was bolted through the rim from outside, and the holes, the flashing and sometimes a chunk of rim cut away for the joist hangers are all paths straight through. In a yard where snow piles against the house, that band is also wet every spring.
The beam pocket. Where the main beam lands in a notch in the concrete, with a gap packed with whatever was handy. It is a large hole at the coldest point in the wall and it is almost always open.
Why this one is worth doing first
It is accessible from inside, it needs no finishes taken down in most basements, it does not depend on the weather outside, and on a typical house it is a day's work. It changes the temperature of the floor above — which is where people notice it, as the cold strip along the outside wall of a ground-floor room. And it removes the path that was feeding cold air into the floor cavities and the bottoms of the exterior walls.
It also has a limit worth being honest about. If the basement is finished, getting at the rim means taking down a strip of ceiling or wall. Sometimes that is one section, sometimes it is the lot, and that is a decision to make with the finish in front of you rather than on the phone. And foam is combustible, so in a space people use it needs the covering the code calls for.
We take care of the work
We quote the job, schedule it and stand behind it, and our own installers do the work on rim joist spray foam insulation Barrhead. You deal with us from the first site visit to the last pass of foam.
Rim Joist Spray Foam Insulation Barrhead: Common Questions
Where exactly is the rim joist? Go down to the basement and look at the top of the concrete wall. The band of wood above it, with the ends of the floor joists landing on it, is the rim.
Ours already has insulation in it. Almost all of them do, and almost none of it is sealed. Pull one piece out and look at the back of it — that tells you what has been going on in there.
Can it be done with the basement finished? Sometimes, by opening a strip. Whether that is one bay or the whole perimeter depends on what the finish is and how it was built.
How much does rim joist spray foam insulation cost in Barrhead? The band prices per board foot of sprayed area at the depth chosen for vapour control, which makes it a small figure relative to any other job in the house. Opening a finished ceiling to reach it is a separate line.
How do I choose a rim joist spray foam contractor in Barrhead? Ask whether the quote includes the beam pocket and the band under the back entry. A price for the straight runs only has skipped the two worst bays.
Size the assembly with the R-value calculator, then get a free Barrhead quote. More on Rim Joist Spray Foam Insulation Alberta province-wide.