Insulating brick building


Old 12-07-01, 03:56 AM
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Insulating brick building

I am renovating an older brick home and want to insulate the walls in the process. This is a two story balloon frame building with walls constructed as follows: brick exterior, studs set off from the brick about an inch, one inch boards, lathe & plaster. I have two situations - those where I've exposed interior walls down to the studs and those where I'm leaving walls intact. Where I have walls exposed, what insulation should I use? Fiberglass seems an obvious choice but Im not sure how Id install it to maintain the airspace between the brick and the studs. Is maintaining the airspace important as the brick may sweat in summer? In the case where I am not removing interior walls, what is the preferred insulation? Again, Im concerned about maintaining the airspace and not putting a material against the brick that would absorb moisture or wick it to the wood. Any suggestions will be appreciated.
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Old 12-08-01, 02:59 AM
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Your concern is correct about puting insulation directly against brick. If you ask any decent mason they'll tell you the same. If you ask this in the brick and masonry forum, they will say the moisture problem will have greater affect with the brick wall than with the wood studs.

The walls you have exposed, building a stud wall and using FG insulation kept an inch away from the wall is fine. The wall that is intact, consider applying rigid board insulation over the wall and sheet rocking over that. The thickness of the rigid board and sheetrock is up to you.

Heat loss calculations in physics, like in ASHREA for heating systems, have factors that dominate. In this case it's surface area. In other words, the larger the surface area, the larger the heat loss. In a two story home, if you were the calculate the surface area of the walls, it would be greater than the surface area of the attic floor and basement ceiling combined. Therefore we can say in a two story home, the majority of the heat loss is done through the walls of the structure. This is based on surface area alone. Putting some type of insulation on the walls is very cost effective.

Hopefully some other commentors on this forum will give you options to insulate the walls. If you ask an architect about the space left between the wall and the brick, I believe they call it a drainage plane. This is where the architect's claim that more structures are destroyed by energy conservationists than by architects comes from.
Old 12-08-01, 03:03 PM
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Greetings, Krieger4

Keeping the fiberglass(FG) away from the walls would help. The only problem is, that the material will still have a dew point within it and pull moisture from the air. ASHREA repors that for every 1% of moisture heat flow increases about 5%. Other government reports show that steady state installtion will have about 9.6% moisture. In older buildings the installtion of FG can accelerate the dryot problem because of the condition of the wood from aging.

I have insulated several of these types of buildings using radiant barriers(RB). In this installation RBs do not have condensation problem and the efficiency is a bout 97% compared to about 10% for FG. There are no carcenogenic problems with RBs due to fibers or the chemicals that coat these products. You have a higher potential for mold problems in an old building which could be reduced by the use of RBs. The RB is also a superior vapor barrier.

Two layers of RB material in ceil'g and walls would surpass the performance of FG by a considerable amount.

Since your type of project is rather involved I would prefer to continue this on my e-mail, [email protected], if you are interested.

Thank you for considering my opinion.
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