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Can I put rigid foam insulation over plaster exterior walls of a brick house?

Darkpie | Posted in General Questions on

I live in central Illinois and it gets very hot or cold during summer and winters here. My bungalow was built before 1900 so there’s literally no insulation in the house except for the attic. I was thinking of putting up some the pink R-10 rigid foam board insulation on my walls and then drywall over them. the walls currently have layer of lath, then plaster, then thin wooden paneling over the plaster. Is it ok to attach the foam boards over the wall without tearing anything down? I don’t mind extending the windows and doors or refitting the electrical outlets. Thanks.

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  1. GBA Editor
    Martin Holladay | | #1

    Adding interior insulation to an older brick home is risky, because interior insulation raises the chance of freeze/thaw damage to the bricks.

    For a full discussion of this issue, with recommendations for safe ways to insulate, see this article: Insulating Old Brick Buildings.

  2. Darkpie | | #2


    Thanks. I saw that article already. Insulating outside the house is not an option for me now. My basement walls are made of brick and cement blocks with fiberglass insulation over it. And I'm basically trying to do the same thing to the upper level except without the mess of tearing out the wall.

  3. GBA Editor
    Martin Holladay | | #3

    My article listed the factors that affect the riskiness of interior insulation. The more exposed the bricks are to rain, and the lower the quality of the bricks, the riskier the job becomes.

  4. Darkpie | | #4

    Martin. Thanks.

    I think I'll go ahead and take the risk then. Do you recommend a specific approach to this project?

  5. GBA Editor
    Martin Holladay | | #5

    All of my recommendations can be found in the article I linked to.

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