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Basement window and door detail

Brian C | Posted in General Questions on

This is probably a pretty easy question but I’m having a hard time finding the information. I am looking for a detail of a basement window installed in a brick foundation wall. I just want to know how to properly frame, install, and flash the RO and window for a water and air tight install.

My second questions is similar. I am looking for the same kind of thing for a basement door. Door is installed at the edge of the slab. What is the right way to isolate it from the concrete. Is a sill pan needed? Are there thresholds specifically made for concrete? Again looking for water and air tight.

Please just point me in the right direction.

Thanks

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Brian,
    To install a basement window, you start by installing a pressure-treated window buck in the masonry rough opening. The pressure-treated buck should be secured with TapCons.

    The gap between the window buck and the masonry should be carefully sealed with caulk.

    If you are installing a vinyl window in this type of opening, there are fewer worries about wall damage than there are with a window in an above-grade wood-framed wall. That's why many builders skip some of the window flashing steps recommended for above-grade windows.

    At a minimum, your basement window should be sealed at the edges with peel-and-stick flashing. To do the best job, include sill-pan flashing, and all of the other flashing steps recommended for above-grade windows.

    When it comes to a basement door for a walk-out basement, your slab should include a recessed "seat" to address water entry. (See drawing below.) If your slab lacks a seat, you should at least include pan flashing. (See photo below).

    .

  2. Brian C | | #2

    Thanks Martin, I still have a lot to learn.

    I had seen the door seat detail before, is the bottom of the seat sloped to the outside or flat? My slab is currently flat and I don't plan on finishing the basement in the future. Would it be better to go with a sill pan or cut a seat into the concrete? I would need to build up a transition at the back dam of a pan like the one shown because the basement lacks subfloor etc.
    How is the door threshold sealed and secured to the concrete in either of these kind of installations?

  3. GBA Editor
    Martin Holladay | | #3

    Brian,
    Many slabs lack the "seat" detail at exterior doors (even though it is a recommended detail). While it would be ideal if the seat were sloped to the exterior, even a level seat is an improvement over having no seat at all.

    Whether or not to cut the concrete is a judgment call. Most builders and homeowners would find it easier to install a sill pan than to cut the concrete.

    When you install your sill pan, you'll need to caulk the gap between the slab and the underside of the sill pan. When you install your exterior door, you'll need to caulk the gap between the underside of the threshold and the sill pan; install this caulk near the inside, not the outside, so that the sill pan can drain to the exterior.

  4. Brian C | | #4

    Thanks again,

    Are the 3 piece sill pan products any good? or is a continuous pan like the metal one shown a better bet? I assume a sill pan is just glued to the slab with PL or a similar product

    If concrete screws were used to secure the threshold they would penetrate the sill pan. Is it okay to use an adhesive to secure the threshold as well? What is the preferred method.

  5. Brian C | | #5

    I have read some of the articles about air sealing gaskets and tapes, and the backyard tape test as well as a couple forum accounts of air sealing strategies and products. I also read the article on JLC about sealants and caulks.

    As mentioned earlier, I need to seal my basement window buck to the adjacent brick. I was going to use sealant after the buck was installed, but I have seen a few cautions around here about that approach. Seems like a gasket or specialty tape is the preferred route. Are there tapes that will stick to brick/mortar and PT effectively? Is a gasket a better bet? or will sealant and a foam sill seal work fine?

    Thanks

  6. GBA Editor
    Martin Holladay | | #6

    Brian,
    Q. "Are the 3 piece sill pan products any good? or is a continuous pan like the metal one shown a better bet?"

    A. Either one should work fine.

    Q. "If concrete screws were used to secure the threshold they would penetrate the sill pan. Is it okay to use an adhesive to secure the threshold as well?"

    A. There is no need to secure the threshold to the slab. Just install a good bead of silicone caulk under the threshold.

    Q. "Are there tapes that will stick to brick/mortar and PT effectively? Is a gasket a better bet? or will sealant and a foam sill seal work fine?"

    A. If you want to use a tape, use Siga Wigluv. It will stick to anything. But a high quality sealant (caulk) will also work fine.

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