Insulating structural brick on interior (Climate Zone 4A)
I’ve been doing a lot of reading regarding how to improve the thermal performance of my finished basement. The house is a Craftsman style built in 1924 with the basement and first floor made of double wythe structural brick with about a 3/4″ to 1″ air gap between the wythes.
I am curious if there is any advice I should follow that is particular to my climate zone or specific brick construction.
The existing finished basement was done pretty poorly, there are sheets of what looks like 1/2″ blue xps foam against the brick between the studs, with no effort made to create a continuous barrier. The rim joist is uninsulated aside from what little insulation is provided there by the presence of fiberglass bats between the floor joists. I plan to rip all of this out.
My initial specific questions are as follows:
0. How worried do I need to be in my climate zone?
1. Is there a threshold r value below which most structural brick of this construction will be okay or is it entirely dependent on my specific brick/mortar construction?
2. Closed cell foam directly on the brick vs using a product like dimple mat to leave an air gap? I thought maybe some holes drilled in the mortar to the center cavity with an air gap product could work well to control moisture especially in conjunction with weep holes on the exterior, but I have obvious knowledge gaps here.
3. Insulating the rim joist–if I decide insulating the brick is too risky, can I spray foam down over the top few inches of it to seal and insulate the rim joist without fear of brick degradation?
4. A previous owner painted the exterior, I believe with a latex based exterior paint. How detrimental is that to my hope to insulate?
5. Do any consultants for brick analysis work on residential/homeowner sized projects? I’ve been in touch with US LimeWorks and US Heritage regarding the mortar on the house but it seems brick analysis is a bit more specialized.
6. On the consultant front-are there any resources for finding “green” minded contractors etc in your local area?
Thanks for any input,
Nathan
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Replies
Hi Nathan.
Have you read this? Insulating Old Brick Buildings. If not, start there.
Though issues with insulating brick tend to be higher risk in colder climates, I think you'd be smart to connect with a local expert on this one, particularly because the brick is painted and that will change how it performs. Best to get this right and do it once.
I agree. I forgot to mention that the basement is walkout and about 80-90% of the walls in the finished portion are above grade, but that there is definitely some below grade portion at the base. I plan to redo the drainage around the house in the spring, the gutters are in good shape but need rerouting at ground level and I'd like to put in crushed rock 4'deep by 1-1.5' wide all around the perimeter of the foundation with perf drainage pipes etc to evacuate water.
Forgot to mention, I did read that article as well as the entirety of the 2012 NREL conference paper/summary on the issue. It's been a while and I was curious if there was anything specific to my construction (brick with airspace vs completely solid) or climate zone to watch out for or that might be working in my favor.
Cheers,
Nathan