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Insulation and barriers on inside of a double brick wall

sunstone | Posted in General Questions on

I am in Toronto Canada doing reno work and have stripped the walls in a few rooms down to the (double layer) brick wall. I am puzzling over what air and moisture barriers combined with insulation would be best. I don’t want to loose too much space. 2X4 wall thickness or possibly up to 2×6.
Can I have foam sprayed directly on inside of brick ?
Or, more conventional , a layer of tar paper nailed to brick(or should I fur this first?), then a wood framed wall insulated insulated.
I am hoping to do my best to insulate between the floor/ceiling joists either w/ sprayfoam if I go that route or fitting rigid insul between joists (can sprayed into place onto the brick.)

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  1. Foamer | | #1

    Hi Richard,
    Building Science Corporation has great research articles on this topic on their website. We are in Cleveland, OH so somewhat similar conditions to yours and have had great results with closed cell spray foam applied directly to the inside of the brick. In addition to air flow and moisture control, you get high r-value per inch of installed material which is often a major consideration with interior retrofits. You can frame out with 2x3 steel studs held back 1 inch from the masonry. This allows the foam to be continuous and prevent thermal bridging.

  2. sunstone | | #2

    That is great news. It had been recomended to me, but by someone in real estate , not necessarily informed on building science. The brick can breath to the outside and the with some attention to detail I should be able to get it airtight on the interior side.

  3. sunstone | | #3

    Reading through various articles on the BSC website. Some great info
    Thanks for that!

  4. GBA Editor
    Martin Holladay | | #4

    Insulating an old brick wall has been known to lead to major deterioration of the brick work, so proceed with caution. I suggest you read this article: Insulating Old Brick Buildings.

  5. sunstone | | #5

    Great article and discusion.
    Especially driving home the need for inspection and handling of water as a starting point.

  6. Envirocon | | #6

    Brick deterioration due to moisture migrating to the outside of the building can be reduced drastically with proper re-pointing procedures. Do not use any cement based mortars as this will dam the water up behind and erode the lime based mortar(I'm guessing here) inside the wall. I use a mixture of type S hydrated lime and sharp sand.

  7. sunstone | | #7

    It just occured to me to ask...Having exposed the brick on the inside should one repoint from the inside? Obviously repointing the o.s... but I had never considered doing it on the inside.
    I'm still considering my options. Like many decisions there is no 1 solution but a range of considerations.
    Thanks all.

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