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Wet plaster connection between walls and ceiling/floor

davorradman | Posted in General Questions on

Just a general question: if both the brick wall and concrete ceiling is covered in wet cement plaster, do I need anything special for connections of wall with the ceiling/floor?

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  1. GBA Editor
    Martin Holladay | | #1

    If a brick wall is supporting a concrete ceiling, you certainly need structural connections (not just gravity) to join the wall and ceiling. In most cases, you will have a concrete bond beam at the top of your brick wall, and the rebar in the concrete bond beam will be tied to the rebar in your concrete ceiling (roof deck).

    These details should be spelled out by your engineer.

    -- Martin Holladay

  2. davorradman | | #2

    Ups, I deleted the relevant part when trying to make the question as short as possible, sorry.

    It was meant to be a question about airtightness.

  3. GBA Editor
    Martin Holladay | | #3

    If you have a poured concrete bond beam and a poured concrete roof slab, you won't have much air leakage there. But since this will probably be a so-called "cold joint" -- because the two concrete pours will be on different days -- it never hurts to run a bead of high-quality caulk along the seam. Once the caulk has cured, you can invite in the plaster contractor.

    All of that said -- where is your insulation going to be? If you are plastering the interior bricks and concrete, I assume that you are planning to install exterior insulation. If that's the case, and if your exterior insulation is rigid foam, you can install the rigid foam in an airtight manner by taping the seams. Make sure that the rigid foam is continuous at the wall-roof intersection -- a detail that can be tricky if your building has roof overhangs.

    -- Martin Holladay

  4. davorradman | | #4

    Thanks again for your help Martin.

    You guessed correctly how thermal envelope will be done.
    I am aware of the rigid foam tapes, but budget being what it is, and the other solution being good enough, I do think we will skip this step, since we are putting cement plaster in the whole of the interior anyways. For this I also have a reliable contractor, since this is basically the only way it's done here where I live, plenty of trained workforce.

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