One of my large upstairs vinyl window frames is leaking rainwater onto the window sill. The base of the frame is filling up with water, which is then overflowing onto the sill, where the window meets it. By comparison, the bottom of the adjacent window frame (which isn't leaking) does not have any water in it.

I don't know whether water is SUPPOSED to get in, but then drain out, or whether it shouldn't enter to begin with. Any suggestions greatly appreciated.

enter image description here

  • 2
    No water should reach the inner sill. Either you have a failing seal or the weep holes are clogged.
    – isherwood
    Feb 10, 2020 at 19:51
  • Larger photos would be great. It's hard to see any detail with them being so small.
    – isherwood
    Feb 10, 2020 at 19:52
  • the black rubber seal on the window looks normal - it just cant cope with being beneath the water line as it were. I'm assuming the issue is with the frame filling up in the first place. should water get in there, and then drain out, or should it never get in there to being with? Feb 10, 2020 at 20:00
  • 1
    Do you see the weep hole at the far right of your photo? Is that draining as it should?
    – isherwood
    Feb 10, 2020 at 20:09
  • 1
    I agree with @isherwood on the weep holes, I see some moisture in the bottom right corner (I think) if the seal is compromised this window may sweat more. But if the little holes normally slots are plugged they cannot drain. A tooth pick is a great tool for cleaning weep holes there may be 4 or more on that large of a window. Sometimes pulling the window and bottom track to clean might be needed.+
    – Ed Beal
    Feb 10, 2020 at 21:12

2 Answers 2


Yes, vinyl windows are designed to allow water to get into the vinyl frame and then drain out the “weep” holes.

Little known fact, the actual “seal” is between the glass and the BACK of the frame. That is to say, there is a black seal strip between the glass and back of the frame. The “stops” on the exterior are just to hold the glass tight to the seal. The stop is NOT designed to stop rain water.

The weep holes are designed to allow the water out of the frame. Perhaps the weep holes are plugged and need to be cleaned, but to answer your question, yes, water is suppose to get in the frame and then drain out.

Btw, the mitered corners are supposed to be welded together. I’d check to make sure the weld has not been broken, because water could then leak out onto the window frame as you describe.


Blocked drainage. Try poking the holes were the water is filling up inside the frame the holes i am talking about is the long slots about 20mm long. Try a plastic straw .to unblock the obstruction. Then pour some water in the holes to see if the water drains outside onto the cill.

  • Hello, and welcome to Home Improvement. Thanks for the answer; keep 'em coming. And, you should probably take our tour so you'll know how best to contribute here. Feb 10, 2020 at 22:40

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