Insulating a Four-Story Brick House
My husband and I just bought a 1924 brick home. It has 4 floors, basement, 1st floor, 2nd floor, and the 3rd floor attic is the master suite. The 3rd floor is newly remodeled and well insulated. There is a furnace on the 3rd floor that heat the upper floors and a furnace in the basement that heats the basement and 1st floor. We recently realized that there is no insulation on the main floor and the 2nd floor. Even with both furnaces running the 2nd floor remains cold. We were going to have blown in fiberglass put in, but then was told it could cause moisture problems. Then we were told to take out the plaster walls, but in rolled insulation and a plastic vapor barrier. After reading one of the blogs on GBA, I’m not sure what to do. We want the 2nd floor to be warm but we also want to make sure we are do u no it correct. We have new windows, new furnaces and the plaster walls are in excellent shape.
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How are the walls constructed? There's a lot of different ways of building a brick wall.
From the inside where we drilled holes. I can see that the plaster is approximately 1 inch thick attached to the lath. The walls have 2x4 studs every 16 inches. The gap between the plaster and exterior boards is about 4 inches. From what I can see its plaster, lath, a 4 inch space, wood then the brick on the outside.
I suppose the question is, can we insulate this old brick home from the inside? Do we used spray foam, rolled insulation, or blown insulation, or do we just live with it the way it is.
Joe Lstiburek gives a talk where he says you should be able to take a plan of a building and draw a line along the building envelope without ever lifting your marker from the page. The idea is that the building envelope needs to be continuous. Older buildings often were not built with that in mind and it is hard to retrofit.
The building envelope has four principle layers:
* a rain control layer
* an air control layer
* a vapor control layer
* a thermal control layer
The question you are going to run into is whether you will be able to implement all four layers, continuously, all the way around the building. Typically where you find problems is where surfaces join -- where walls join the roof or floors.
Here is something to keep in mind:
“Sometimes you just don’t insulate the walls,” says Straube. “Even if the walls are left uninsulated, you can often reduce heating demand by 50% by addressing air sealing, the basement, the roof, and the windows.”
Use this link to read the entire article: https://www.greenbuildingadvisor.com/article/insulating-old-brick-buildings
Note that this article addresses load-bearing brick walls. It doesn't sound like your home is constructed that way, correct?
There are a lot of threads on here on insulating older balloon framed brick veneer houses:
https://www.greenbuildingadvisor.com/question/how-can-i-insulate-a-wall-with-interior-sheathing#comment-146800
You can also read through this:
https://www.buildingscience.com/sites/default/files/bsc_to2_1_3_final_expert_meeting_report.pdf
The usual answer when it comes to the possibility of insulating these older houses is "it depends".