How do you insulate a 1950’s brick building?
The building is a 1950s apartment building in Denver that we’d like to insulate, with the following wall construction:
Brick exterior, uninsulated wood frame, with plaster on the interior. Additionally, the bathroom currently has a passive vent, and the kitchen has no exhaust fan, so there is a potential for moisture buildup.
According to Cold Climates (p 146), with a vapor semi-impermeable
exterior (brick) and no sheathing insulation, a vapor barrier (or retardant?) would be
required with a vapor permeable interior (plaster).
I’m generally loathe to do a vapor barrier, especially in our dry climate, but I can see the point here, so I’m tempted to recommend a vapor retarding paint.
Thoughts? Thanks!
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Replies
Mark,
Assuming that your basic question is found in your title -- "How do you insulate a 1950's brick building?" -- then worries about a vapor barrier are the least important issue.
1. Do you have a structural brick wall? Or is the wood-frame wall the structural wall, with brick veneer?
2. I don't agree that a brick wall is "vapor semi-impermeable." Brick and mortar are fairly vapor-permeable.
Martin - yes, I got so involved in the details, I forgot to re-ask the question. We're exploring the idea of drilling and filling (from the inside) the cavities with either cellulose or fiberglass.
1. I'm not sure if it's a structural brick wall or not. I was able to get a probe into the wall near an outlet, and it appeared to be an empty cavity 4"-5" deep.
2. So, if it's fairly permeable, it seems that the wall could dry to either side, and wouldn't require a vapor retardant paint?
Thanks!
Mark,
It would be useful to know whether the bricks or the wood frame are structural. You might be able to determine the answer by a visit to the attic; look at the perimeter and see where the ceiling joists and rafters are bearing.
If your wood-framed wall has exterior board or plywood sheathing, that would be a clue that the wood-framed wall may be structural.
There are many factors to consider before insulating the interior of a brick wall. In some cases, making the bricks colder can make the brickwork more wet and more susceptible to damage from freeze/thaw cycles.
I wouldn't recommend installing cellulose in contact with a brick wall. Most experts prefer the use of spray foam, but there are many variables to consider before you decide on a plan.
Martin,
There was no attic space - just a flat roof with no apparent access hatch. I'll talk to the owner and see if they have any open access to the wall - there wasn't any in the unit that I inspected.
Are there good spray foam systems for drilling and filling? The ones I've seen have been questionable.
If you are in the insulation business in Denver, then you know Dennis Brachfeld. He isn't afraid of drilling and filling with foam in our dry climate. I've done it on one of my own buildings, but I can't prove that it is saving any heat at all. If you own an older "3-story walkup" it could be triple-wythe, after 1935-1950, it's more likely to be CMU and one wythe of brick. Filling the voids of CMU is also pretty ineffective (I've tried that too).
I think you are stuck with building a new sheetrock interior wall, or submetering heat to your tenants.
Thanks, Kevin. I'm up in Boulder, so I don't know Dennis, but it's always good to have recommendations.
Would you say that your tenants are more comfortable in the blown-foam building?
I couldn't measure or feel a difference in my building. However, Dennis says his clients are very happy.... for example he'll do a "cold room" and it usually becomes the most comfortable room in the house. He's never done an entire house because of the expense. He fills that gap between the wythes. You'll have a similar gap between your brick and block.