Rim joist spray foam insulation in Blackfalds treats the band of timber that sits on top of the foundation and carries the floor above it. On a stock this young it is the item that most reliably justifies itself, because it is the detail a new house is least likely to have right.
The one detail a new house rarely gets right
Everything else in a modern build is specified, measured and inspected. The band is a narrow strip around the perimeter, it is awkward, it takes time to do properly, and there is no number attached to it that anybody checks. So it gets a piece of batt pushed into each bay and the ceiling goes on. That is the standard outcome on a Blackfalds house rather than a poor one, and it is why this is worth buying on a house that is otherwise perfectly well built.
What the builder put in there, and why it does not seal
Batt is a resistance material. It slows heat moving through it and it does nothing about air moving around it, and the band is fundamentally an air problem: the joint between the sill plate and the top of the concrete, the joint where the band meets the subfloor, and the gap at each end of every joist bay. Batt covers those joints without closing them. Closed cell foam goes in as a liquid, fills the joint and stays stuck to both surfaces, which is why this one detail is worth a different product from the rest of the house.
Before the basement gets developed, not after
The practical argument here is timing, and in this town it is unusually clear. A large share of these basements are still open, so every joist bay is visible, there is nothing to demolish and the job is done in part of a day. The moment a ceiling goes in that changes completely. Anybody planning to develop a basement should treat the band as part of that project rather than as something to consider later, because later means opening what was just built.
Three winters in, this is what people report
The change shows up upstairs rather than in the basement. The floor stops being cold along the outside walls, the room stops having a cold edge to it, and the furnace cycles less through the evening. Nobody notices a resistance value. They notice being able to sit at the end of a room in January, and on a house in this town that arrives from a job that took part of one day.
Rim Joist Spray Foam Insulation Blackfalds: Common Questions
Our house is only a few years old. Is this still worth doing? It is the item most worth doing on a new house, because it is the one detail that is rarely right.
Does the insulation already in the bays have to come out? Batt does not seal the joints, and the joints are the point. It comes out.
When should we do it? Before the basement is developed. Once a ceiling is in, reaching it costs several times as much.
Size the assembly with the R-value calculator, then get a free Blackfalds quote. More on Rim Joist Spray Foam Insulation Alberta.