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Front window leaks during heavy rain with southwesterly winds

Front window leaks during heavy rain with southwesterly winds


Old 11-28-10, 07:02 PM
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Front window leaks during heavy rain with southwesterly winds

I have a two story home with vinyl siding (no Tyvec wrap ) and a covered front porch. During periods of heavy rain with strong southwesterly winds water drips in through the top of one of the windows underneath the porch roof. It's a double window and it only leaks on one side. The water enters not where the drywall meets the windows, it's a seam in the middle of the frame itself. This happens about once a year.

I'm guessing that water is getting behind the siding, trickling down the exterior wall, and entering through a gap between the wall and the window frame. If I were to remove the layer of siding and run a bead of caulking along the top of the J-channel (at least that's what I think it's called), would that prevent water from getting behind the window and leaking into my house?

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Old 11-28-10, 07:19 PM
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Sad to say, with no housewrap, you may already have more problems than you know about. A little caulking isn't going to solve your problem. Caulk is rarely a good solution to a leak.

Water is probably running down the wall and is getting behind the nailing fins of your windows... or possibly there is a gap in the nailing fins either at the corners of the windows, or between the two windows in question.

If there is a roof over the windows, they shouldn't be getting wet at all, should they? If so, it's likely that water coming in around the j-channel of an upstairs window is letting water get behind the wall flashing of the roof.

Removing siding and j-channels over the windows would allow you access so that you could install window flashing tape over the nailing flanges on top of the windows. The window flashing tape would stick to the sheathing, and would provide you with "some" protection. But this is really just putting a band-aid on a larger problem.
Old 11-28-10, 07:36 PM
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The majority of windows (even in a hole in a Tyvec wall) are not installed properly.

Look above for the source of leakage. Even if there is a roof above the window, the moisture could be in the wall above that and migrating down until it meets a barrier.

Vinyl siding is notorious for water penetration. A j-channel is just to divert moisture and divert it downward.

Windows should be installed with flashing under the moisture barrier above, but without a moisture barrier, it will just go downward and sometimes laterally to find a weak point or exit.

If this has been ongoing, I would suggest getting someone with a moisture meter with long probes ($" or so) to check under the window, especially if you have fiberglass, that will hold moisture to feed possible mold growth.

What you are seeing is not the leak, but where it shows up inside.


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