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Community and Q&A

Insulating inside of brick wall

KennyPa | Posted in General Questions on

I am renovating a 100 year old house, it has load bearing exterior brick walls (2 layers), and the original plaster and lath was set off about 3/4″ off the inner brick face.
Needless to say I would like to insulate the interior face of the brick.
I’m framing with 2×2 almost against the brick just to run some cables and outlets and sheet rocking it up.
I saw post regarding this topic, but they were dated a while back, and I wanted to see if there has been any new advances or suggestions to this.
I get the general idea of needing the brick to breathe and dry on the inside, but not sure if that is still necessary with a double wide brick wall, although I cannot confirm yet if there is a space between them.

Thank you,

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  1. Expert Member
    Dana Dorsett | | #1

    With a solid double-wythe brick wall it's still useful to have an air gap between the brick and the finish wall interior as a capillary break. Depending on climate and how the floor/ceiling joists are supported it's sometimes OK to seal and insulate the wall with some amount of closed cell polyurethane spray foam as the capillary break. In some other climates if there are sufficient roof overhangs and bulk water handling details it can even be OK to dense pack cellulose up against the brick.

    If going for a cavity wall solution it doesn't have to be very deep to function as a capillary break- a half-inch is plenty, though 1" is more common. Using strips of foam board as spacers and installing asphalted fiberboard sheathing or foam board as the exterior side sheathing of your finish wall assembly can work, but again local climate matters.

    Where are you?

  2. GBA Editor
    Brian Pontolilo | | #2

    Hi Kenny.

    There is a lot to consider when insulating a brick building from the interior. Is this the article you read, from 2011? Insulating Old Brick Buildings It is still relevant, so if not, I suggest you use this as a starting point, and consider having a local expert take a look at your project.

  3. KennyPa | | #3

    Than you both, yes, that is one of the articles i read.
    The house is located in the New York, and there is a 2' overhang of the roof.
    The floor joists are supported by the inner brick layer.

    1. Expert Member
      Dana Dorsett | | #4

      >"The house is located in the New York..."

      Since New York spans from climate zone 4A to the cold edge of zone 6A, narrowing that down a bit is going to be necessary to advise further.

      >"... there is a 2' overhang of the roof."

      That's great if it's 1-story, less so if it's a 3 story or higher.

      >"The floor joists are supported by the inner brick layer."

      Once there is a layer of insulation between the interior and the brick, the brick will be colder and harbor more moisture, which is potentially risky for the joist ends. The more precise location/climate zone can affect how risky it is to insulate around joist penetrations, and how to go about it.

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