Insulating existing double-wythe exterior brick wall
Hello,
My wife and I recently bought a 1970 home in Virginia (climate zone 4A). The exterior wall is structural brick (2 wythe) with no insulation (only 1x furring strip with drywall). Heat pump (in unconditioned attic) that does not do a very good job in the winter and RH in the 20s during winter. We are trying to figure out a way to make the house more comfortable during the winter. Sealing all penetrations in attic and adding blown-in insulation to R40 has helped alot, but we feel that all the heat is just exiting through our exterior wall (dry drywall feel really cold when touching it). Our question is, if we decide to beef up out exterior wall, what would be the best composition? After doing research we came up with the following 2 options(starting from the exterior).
Option1:
2 wythe brick wall (existing)
Tyvek air barrier (new)
2×4 wood stud (new)
Rockwool batt insulation (new)
Painted drywall (new)
Option2:
2 wythe brick wall (existing)
Closed Cell EPS Foam Panels (new) (https://www.insofast.com/insulation-panels-for-interior-residential-walls.html)
Painted drywall (new)
We read zone 4A does not require vapor barriers so i guess that answers that. Does anyone see any issues with this? potential room for mold growth? condensation? etc? The humidity level in our house is kinda high during the summer, so will beefing up the walls make it worse or help?
Thank you all for your input!
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Replies
Hi user-7599460 (it would be great to get your real name).
The danger when insulating structural brick walls from the interior is that the new insulation can put the brick, and hence the structure at risk by putting it through freeze/thaw cycles that were less intense when the building was uninsulated, because the walls were warmed by the house's heating system through the winter. Once insulated, the brinks will get colder in the winter. If the bricks are also holding a lot of moisture, you can create problems. I suggest you read this article before you make any decisions about how to proceed: Insulating Old Brick Buildings
Hi Brian,
Thank you for your input! The article, under "Climate Matters" states the following:
In general, brick walls in cold climates are more susceptible to freeze/thaw problems than brick walls in warm climates.
“It’s rare that we have to worry about freeze/thaw problems in places like New Jersey and New York City,” says Lstiburek. “I don’t think we have much to worry about in Boston. But I’d be real nervous in Burlington, Vermont, and I’m real nervous in Ottawa, and I’m kind of semi-nervous in Toronto. … When we start getting into, say, Portland, Maine, I’m going to say you probably shouldn’t insulate more than R-10.”
This leads me to believe that if cold weather in New York is rare to have to worry about freeze/thaw issues on brick, then i shouldn't have to worry at all about the cold weather further south (Virginia). Am i reading this incorrectly? Please advice.
Thank you again!
Maybe not, particularly if you don't have water issues. However, it's good to know the concerns, some things to look for when inspecting the brick. And I think some of the best advice that the article offers is that if you are not sure about the situation, hire an expert for a consultation. It could pay for itself by preventing costly repairs down the line.
Brian
That house must've been built before the energy crisis! I guess you're dead set on a brick exterior? Interior work will require all new electrical, maybe some heating changes, window and door jamb extensions, new baseboard, flooring revisions.