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New vinyl replacement windows – gap between framing & window jamb, air seal?

jonnc85 | Posted in General Questions on

I’m finally getting around to replacing some rotting wooden windows with new vinyl replacements. I took off a piece of the brick mold today and I’m not surprised to find a fairly large 1/2″ gap between the old window jamb and the rough framing. There’s some random batt insulation stuffed in parts of the holes, but not all of them.

* First of all, is this flashed right? There’s some sort of vinyl-like house wrap going around the rough framing member. I know nothing about flashing really, especially on brick veneer homes. This home was built in the fall of 1999, the walls have no weep holes (but it’s a peer and curtain wall foundation – I think you don’t need them for that), and I’m in Eastern North Carolina. The caulk around the brick mold split over time and water was getting behind here, so there is some rot on the outer OSB under the black wrap, but nothing too bad I don’t think.

* Spray foam – I have a feeling I should try to seal this gap with window and door great stuff, but should I? Will it interfere with the vinyl-like wrap?

Photos below show the brick mold removed. The 1 1/2″ wide stop is still on in the photos. I’m replacing all the stops, brick mold, and trim with the PVC kind. Thanks Martin & anyone else for your help!

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  1. Jeffrey_Savage | | #1

    I would suggest a properly sized backer rod placed into the gap then caulked with Sonolastic NP1 (or similar product). Spray foam may crack as the building expands and contracts in different weather. Caulking (with the backer rod in place) can give you some flexibility.

  2. GBA Editor
    Martin Holladay | | #2

    Lots of issues here.

    First of all, I'm not aware of any way to properly install brick veneer on a wood-framed building unless you include base wall flashing and weep holes at the bottom of the wall. That said, many builders don't know that, so there are lots of other buildings like yours.

    One of your questions is easy to answer.

    Q. "Is this flashed right?"

    A. No.

    Why? Because you wrote, "Water was getting behind here, so there is some rot on the outer OSB under the black wrap." This is a big red flag. You have expensive repairs on the horizon.

    You need to ascertain the extent of the OSB rot, which may require removal of sections of the brick veneer -- potentially around all of your windows. Some exploratory holes from the interior side may be helpful as you assess the extent of your moisture problems.

    Before you install any replacement windows, you need to:

    1. Assess the extent of the OSB rot.

    2. Replace rotten OSB with new OSB or plywood.

    3. Repair the housewrap (lapping properly).

    4. Properly flash every window rough opening before installing new windows.

    Good luck.

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