Hi all, I have a 1910 house in Toronto ON. Double brick (with air gap) on the first floor. Second and third floors will be cedar-shingled, cedar breather, typar or felt fully caulked and taped, tongue and groove sheathing, then 2×4 framing that sits on top of exterior wythe of the brick wall below. Second floor joists sit on top of the double brick wall.
We have gutted the house and I need an insulation strategy. Second floor is fully framed with studs, while first floor had 1″ vertical strips on the brick that the lath was attached to. My current thinking is to build out the main floor walls and spray 2″ of closed cell foam against the brick to get ~R14. My thinking here is that it is enough to air seal and prevent moist interior air from condensing on the brick, while significantly reducing heat loss from its current (0 insulation) state.
Upstairs, I do not want to lose any space and therefore I am considering two options. Option 1: R14 rockwool + intello or membrain smart vapor control. Option 2: 3-3.5″ of closed cell foam that would provide more R value and potentially better air sealing, but is not easily removed in 50 years when the house is renovated next. I also thought maybe 4″ of blown in cellulose could be an option in the cavity.
Adding exterior insulation is not an option because the house is designated under the heritage act.
Any thoughts on my current thinking would be greatly appreciated.
Thank you
Replies
For a major renovation, you may be expected to bring the insulation up to code.
(so questions for your local building permit and inspection office)
My observation is that you may want to consider how to insulate the rim joists at each floor you have access to. interior vapor control should be connected above, through, and below these areas between floor and ceiling.
Thanks, Mike. That is a great point. Luckily we are allowed to leave it in it's existing condition, so we are working on insulating it in the best way we can without compromising too much space.
Then I would shoot for R 15 of rock wool batts. Whatever you put under the cedar needs to be able to breathe to allow vapor to exit to the outside.
The rim joists are worth insulation and vapor control, on both levels.
An interior vapor control on the interior side of walls on both floors, connected across the floors between, and sealed to a similar barrier in the upper floor ceiling is a good idea.
I would hesitate to fill the air gap between brick layers. It is there for a reason.
Your approach to insulating the double brick walls on the first floor with closed-cell foam and considering options for the second and third floor such as rockwool and vapor control, closed-cell foam or blown-in cellulose is a good approach. It's important to keep in mind that adding exterior insulation is not an option due to the house being designated under the heritage act. It's always a good idea to consult with an insulation professional to ensure that the plan is executed correctly and meets the building codes and standards.
Great to see that somebody is giving thought to reversibility, the concern for undoing what seemed like a good idea at the time. Spray foam that cannot be removed when something better comes along can ruin a historic surface or building envelope. If a structure is considered important enough to be placed on a heritage list or something similar, thought must be given to how it can be returned to it’s original form if deemed necessary in the future. So much of historic preservation is repairing the damage created by better ideas.