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Water leaking from Arch Window to double hung windows.

Water leaking from Arch Window to double hung windows.

Old 12-03-11, 10:45 AM
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Water leaking from Arch Window to double hung windows.

We bought this house about a year and a half ago. We have two rooms with the same setup you see here:

When the rain is heavy enough to beat against the arch windows, water begins to drip on the inside top of the double hung windows:

I have looked at this pretty carefully and the sealing tape seems to be properly applied around the arch windows under the vinyl siding.

There is always water visible in the arch window weeps:

The only area I can see that might be undersealed is at the ends of the transition panel between the arch window and the double hung windows:

Despite what it looks like, the sealing trim piece between the two windows is well sealed across the entire width, except for this last inch or two of overhang at the end.

Both sets of windows are leaking in exactly the same manner.

The way I see it, there are two main possibilities:
1. The water is getting in through those imperfectly caulked end strips between the two windows.
2. The weep holes cannot keep up with the amount of water washing down the face of the window and is somehow ending up on the inside.

I am looking for solutions and any similar experiences other people have had. What I do not want to do is seal this up, only to find that I am trapping water and causing an even bigger issue.
Old 12-03-11, 12:56 PM
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The H-mull (horizontal piece between the 2 windows) is the first thing I would suspect. I would have used a white PVC sealant on the top edge, but if you were going to recaulk the top edge of it I would recommend white OSI Quad (Lowe's carries it) and use a very fine tip.

The 2nd area of concern would be the side of the H-mull (the channel where your vinyl siding sits). There's probably no good way to check this without removing some siding, which isn't too hard to do if you have the correct tool. (Google Malco Sideswiper) It is kind of a crummy way to seal windows together, but you would probably also need to caulk the snot out of the joint between the windows which appear black in the photo. While the siding is off you would also want to ensure that they put a butyl window flashing tape over the vinyl nailing fin. If they didn't, it would be wise to remove all the siding around the window in order to do that. Vinyl siding allows water to get behind itself along every edge, so just imagine what would happen if water was running around the semi-circle and reached a gap in the nailing fin where the two windows meet. I can't tell if that black stuff with the numbers and letter is butyl flashing tape or if its housewrap or what. But if it isn't sticking to the window or it isn't done properly that would be a problem area too.

Only other thing it could be is that if they screwed those 2 windows together, those screws could be conducting water down the threads if the screw heads weren't sealed. Those screws would penetrate the chamber where water collects and runs out the weep holes. I have also seen weep holes get plugged with dirt and dust, so you might take a pipe cleaner or air nozzle and try and clean them out. Sometimes there is a snap in cover on the interior that you can remove, and you could see if this is full of water or not, which would indicate plugged weep holes.

Good luck with that.

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