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Insulating brick building

Robert_Williamson | Posted in General Questions on

Hello Everyone;

So, I am aware of the importance of providing a ventilation gap between reservoir claddings (such as stone or stucco) and the rest of the structure, because of inward vapour drive.

Let´s assume I have an old brick wall that I will insulate from the inside. I place a frame wall on the interior side and put some batt insulation on that. Closing with drywall.

Will I have the same problem with inward vapour drive? There is a lot of talk about reservoir claddings, but how about reservoir structures?

Thank you in advance
Robert

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Replies

  1. Jon_R | | #1

    Joe L's definition of reservoir cladding includes brick. I assume that facing vs wall doesn't matter.

    https://www.buildingscience.com/documents/building-science-insights/bsi-061-inward-drive-outward-drying

  2. GBA Editor
    Brian Pontolilo | | #2

    Hi Robert.

    If you are asking about brick veneer (a wood-framed building with brick cladding), it needs an air space just like stone and stucco and if that air space doesn't exist between the brick and the sheathing, you should provide for it inside the assembly before insulating, similar to the detail shown in this article: Insulating Walls with no Sheathing.

    Structural brick buildings are a whole different animal and the answer depends on a lot of variables. If that is what you are asking about, I suggest you read this: Insulating Old Brick Buildings

    1. Robert_Williamson | | #3

      Hi Brian;

      Thank you for the reading material.

      Yes, I was referring to structural brick buildings. Imagine a brick wall insulated from the inside and drywall. Or with no insulation at all, just drywall. Will there be any problem with inward vapor drive ?

  3. Expert Member
    Dana Dorsett | | #4

    >"Let´s assume I have an old brick wall that I will insulate from the inside. I place a frame wall on the interior side and put some batt insulation on that. Closing with drywall."

    That will have a real problem without a fairly good capillary break between the batts and brick.

    If not a vented air gap, an inch or more of 2lbs density closed cell polyurethane applied directly to the brick can work, with the stuwall and batts snugged right up to the foam.

    With any insulation approach it's important to pay attention to the details of how wooden joists are hung on the brick. The brick will be colder and wetter than previously, potentially putting any wood that has contact with the brick at risk.

    In some climates and buildings the brick can become more susceptible to freeze/thaw spalling due to the higher moisture contact that occurs after insulating. Where is your building located, how tall is it, and how deep are the roof overhangs?

    >"Imagine a brick wall insulated from the inside and drywall. Or with no insulation at all, just drywall. Will there be any problem with inward vapor drive ?"

    Yes there WILL be a problem with inward vapor drive, more pronounced if the building is air conditioned. There is a capillary draw issue too, which is why many old-school uninsulated brick buildings mounted plaster & lath on furring (with an air gap to the brick ) rather than plastering directly onto the brick.

    1. Robert_Williamson | | #5

      Dana;

      Thank you very much for your input.

      I am located in an easy climate (Zone 4). I understand the problem with capillarity, especially when the building is not protected against rainwater.

      However, imagine I have an unprotected wall, insulated on the inside with batt insulation and non-paper faced drywall. Cant the capillary water moves towards the interior through this vapour permeable assembly and then be removed by the indoor mechanics ?

      Does It make any difference if I do not insulate the wall? Just placing a service cavity with non-paper faced drywall?

      Thanks!

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