Basement window very slow leak.

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Posted by: from Gibbons
9/3/2018 at 2:29:23 AM


I have a basement window that is slowly leaking.

The window surround on the inside is looking like moisture is warping the corners.

The window on the outside has a certain tape all around it to seal it, and also doesn't have the top metal strip.

This window was like this when we bought the house.

I've been putting it off getting somebody to come over to look at it, but then I found this website.

I included a pic of another basement window that has the metal top.

Basement window very slow leak.
Basement window very slow leak.
Basement window very slow leak.
Basement window very slow leak.
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Date/Time9/3/2018 at 3:01:58 AM

Windows are typically $500 labor for remove and replace. Might be time for an upgrade since the labor is the same taking a window out anyways. I can't see the pic, but where there's water, there's mold and rot. If you want to do it right, pull it out and install properly.

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Date/Time9/3/2018 at 10:37:10 AM

Concerning your basement window the best thing you could do is call a trusted Pro window installer in your area and have a new one installed. If you do not replace the window then have it capped with aluminum on the outside and caulked. Hope this helps you out. Jeff

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Date/Time9/3/2018 at 12:11:47 PM

Hi Mike,

If you're handy and want to attempt the repair yourself it's fairly straightforward.

At this point you're going to have to remove the window completely and expose the wood framing. It will need to be replaced more than likely. It should be a 2x4 wall an air gap (1") then the concrete. However, for the sake of not having to do more work than necessary on your part, replace the frame exactly as it was originally built as best as possible - take pictures it'll help.

Note: when you rebuild the frame build it 1/2" bigger all the way around, this allows you to shim, but more importantly insulate with sprayfoam like you're supposed to.

Once you've gotten the frame rebuilt you can install the window. Shim it, level and square it. After that you'll be going outside to finish the exterior. At this point depending on what type of siding you have (Vinyl, Aluminum - I can't see the picture) there are drip ledges you'll install above and below the window. You'll also want to take a look into Flashing Tape, it replaces the need for ridgid aluminum flashing and allows you to seal non-linear opening typical of a retrofit. Do not, use Red Tape (or Blue Tape) to seal the window, it will not last, use flashing tape in it's place.

Obviously, a good windows and doors contractor can do this all for you, so my suggestion is to go that route if possible.

However, if it's not, then going into your local Home Depot/Lowe's/Rona/Home Hardware and talking to the window/door department, they can direct you to all the materials you'll need to get the job done right.

If you're doing it yourself, YouTube is your friend. Look up reputable channels and do your research!

Hope that helps, good luck!


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Date/Time9/4/2018 at 1:26:32 AM

Not sure if you're intending to replace the window. If you are and it's a bedroom window mention this to your window supplier so they will ensure you have a window that meets egress.

If you're replacing the window, first disassemble the existing window to see if there is wood that requires replacement due to water damage and to get the proper sizing for the replacement window.

Best to leave an approximately 1/2" gap all around to be filled with insulation & sealant.

You mention the flashing as per your accompanying photo. Head flashings are described in Section of the Code; they must extend 50mm upward and inboard of the sheathing membrane (ensuring a 'shingle effect'), have a slope of min. 6% (obviously deficient in your photo), lap min. 10 mm vertically over the top edge of the window, and extend min. 5 mm beyond the outside edges of the window.

Often it is difficult in a retrofit situation to do the head flashings in a way that satisfies Code; much easier with new construction. Selecting windows with a nail fin is always preferable but depending on your situation you might have to settle for windows without fins.

Sealants are described in; they must conform to ASTM C 834, ASTM C 920, ASTM C 1184 or ASTM C 1311 (check labeling carefully if shopping at your neighborhood hardware store).

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