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33 Responses to “Leaks and Problems with Vinyl Windows”

  1. Rafael Pérez Molina

    Another big issue I perceive on PVC windows is cristalization due to UV exposition. It would be interesting to know your point of view about it.

  2. Mark – Here is an interior shot of a vinyl window where the little window drain slots couldn’t keep up with the rain. I had about 1,000 of them on this project that were suspect. Some of these windows we could “port out” and increase the flow, but a few were too warped to be dependable even with adequate drainage and had to be replaced.

    Also, I included some photos of the rear hatch glass that exploded in my little electric car. The factory didn’t want to warrant it because, “One had never failed before due to a defect”. I said, “Well you got one now!” Look at my notes and you can see the defect clearly. After their engineers looked at this, I got my $700 piece of glass replaced under warranty…

    I have an 70+ window residential project starting shortly. New home, hand made wood windows, reverse slopes, no weather strips, literally sheets of water entered at some locations during a bad storm – Lots of interior damage.

    John McReynolds, CGR GMB
    Home Defect Analysis & Solutions
    Comprehensive Claims Solutions, Inc.
    Houston, Texas 77080
    leak at bottom of pvc window

    leak at bottom of pvc window

  3. We are saving up this year, so as to not have to face another winter with jack frost blowing threw our home. Time to replace all the windows!

  4. “One had never failed before due to a defect”. I said, “Well you got one now!”

  5. Thanks Mark. I enjoy reading your materials, very interesting and informative. Keep up the great work.


  6. Hello,
    You are providing some great advice on the website with regard to the water issues. The one thing that I noticed with regard to the ice damming, that was over looked is the root cause of ice damming.
    It is caused by the heat from the house melting the snow at the roof interface and forming ice at other parts of the roof that are cold, typically by the gutters or exterior edges.
    This problem is typically a roof ventilation issue.
    This also can be indicative of other problems such as insulation properties being lessened through condensation on the roof, roof rotting out and ice piercing the roof membrane.
    We are currently introducing roof vents into the chicago area that are designed especially for flat roofs. We have seen a lot of issues with flat roofs lately in buildings that are a few years old. Most times it is due to the impermeable moisture barriers being penetrated too often with can lights, speakers and other in ceiling holes, allowing interior moisture into the attic that ends up condensing in summer when the ac chilled air meets the super heated moist air. Leaking can lights are the normal result.
    In winter the moisture turns to ice if not eliminated and can compress the insulation.
    Check out our vents at
    We are the supplier in the US from the midwest to the west coast.
    Thank You
    Ventaroof LLC

  7. This is great information about vinyl windows. It shows how important it is to get windows and service that is guaranteed. If you need vinyl window repair or replacement in your home, stop by and contact us for a quote.

  8. Very informative info, Mark.

    Please check out this window made in Indiana. Alum. exterior with a vinyl interior married with urethane foam.

  9. window pvc is leaking from bottom onto sill leaking at bottom where 2 windows are attached together example { ! }{ ! }

    “(leak on sill)

    any ideas thank you very much

  10. Hi! I was googling water leaks, and stumbled across your site. Wow, lots of great information! I just noticed water damage to the wood trim and drywall on the bottom, interior corner of my daughter’s double hung vinyl windows. There is also a small spot of soggy drywall on the ceiling below these windows. I’m obviously concerned, and am planning to go back to both my window, and siding contractors to fix the source of the problem. Unfortunately I don’t even know where to begin figuring out where the water is coming from. It’s definitely an outside problem as there is no plumbing on that side of house. Any suggestions as to the source? I’d like to be informed prior to talking to the contractors so they’re not “fixing” the wrong (read easiest, cheapest) thing. Thanks for you site and feedback!

  11. Window leaks are a high priority problems. Left unattended, leaks through windows or walls can cause extensive and expensive water damage.

  12. Vinyl windows are one of the most durable, easily maintained windows you can choose when upgrading the windows on your home.

  13. If you have vinyl windows, please take a moment to join our “Rate Your Vinyl Windows” survey. It’s at the bottom of Leaks and Problems with Vinyl Windows.

  14. UPVC windows are good alternative for old ordinary windows as they are thermal resistent. You have also added some cons of UPVC which I found informative, thanks for sharing.

  15. Mark,

    Great site, lots of great information. Just built home in SE WI. Many of my windows have condensation although I have humidity down to 40%. But now I’ve noticed I have several windows that area leaking air where the sash at top of bottom window meets the middle (locking area) on both sides. How do I fix that. The windows are supposedly Windgate by Alliance and have a 5 year warranty. Trying to get builder, installer, etc., to respond is a joke.


  16. Hi Ron,
    If possible, send a few pictures to and I will try to help.

  17. We do not have condensation, but my how the windows whistle when the wind blows from certain directions. The air leak we are having is at the top of the window. Any suggestions to fix it?

  18. Assuming the windows that whistle are operable, you may need to add a thicker weatherstrip or some sort of additional latch that closes the top corner more tightly.

  19. Nice site analysing upvc issues. Many are poorly fitted. I had all my patio doors/windows leaking water and found an easy way to fix them so I made a video that may be of interest to others with water leaks. See here:

    Regards Jon

  20. What I am having a problem with is crank out vinyl windows and we have some heavy winds that have bent the vinyl frame where the crank is and so this area is bent out. Now we have not as good seal on the window.

  21. This sounds like permanent damage and may warrant getting a new sash.

  22. Replacement windows without exterior perimeter flashing are an irresponsible product. There is no way to effective seal water out. Relying on caulking means it is only a matter of time before water infiltration occurs.

  23. I just got new vinyl windows, and there are screw tips protruding between glass panes, on left side of each window.. There are two screws, one 1.5″ from the top and another one 1.5″ from the bottom. I thought that there should be nothing protruding between panes, as windows are supposed to be sealed. Is is a defect and will it present a problem with condensation? Protruding tip is about 0.25″ long… Is it normal? Windows were installed a week ago. Thanks!

  24. Hi Vera,
    Can you send a few pics of this to me at
    Thanks, M

  25. I had 2 custom made (language from contract) Vinyl Double hung windows, 2 full grids 6/6, wide flat, 1 mull 2 metal rips costing me $1 328 dollars installed in my condo 7/7/14. The window is leaking. The caulking/sealant is caving/sunk in at the bottom, especially at the left corner. I called the contractor and the man who installed the windows is coming out tomorrow morning to look at it and put more caulking/sealant in where it is wet and caving in. Do you think this is going to fix the problem? I really don’t know what to do. I’m a librarian and the best I could do was google the internet and I found your website, which is excellent. Help me with some advice as to what to do or say tomorrow, please. Thanks for listening, Sincerely, Linda T.

  26. Hello , I am studying up on vinyl windows so I can budget for replacement of old wood and storm from 1968 possibly. In my area window world seems to have best price and warranty yet I have noticed a defect in their product at a friends house that worries me. Its a bow in sash at center of window and is quite noticeable to the eye , mine atleast. I see your explanation or example above and that is exactly what I see and don’t want inside 2 years .Can you share w me branding or make or even properties to look for within a brand that will keep that from happening please . Im in Nashville Tn. I also stopped in at a Pella store and they are priced out of my pocket . I will have 12 windows 5 are 77 x 39 and others are normal size if size is a consideration when worried about stresses and bows.
    thanks , John

  27. One last thing you failed to mention about vinyl windows.. carcinogen. As that chloride is exposed to sunlight it vibrates away from it’s molecular structure and creates a chloride gas that emits into the home. After the 1st chloride dehalogenates off the frame, many other chlorides next to the initial one begin to do the same in an accellerated rate. As we all have learned plastic are bad for you like BPA, Vinyl or PVC is one of the worst for your health. Vinyl also doesnt block out sound very well due to its spring-like molecular structure. Where i am from, Texas, vinyl softens, ripples and warps in the heat of summer. Vinyl also is no match against hail. Some countries in europe have outlawed vinyl windows and blinds due to there carcinogenic properties and collateral damage due to excesive shrinking.

  28. Thank you for the info on your website! We have double hung vinyl windows all through our house and we find that bugs can just walk right through between the windows. From reading your site I will have a look and see how warped the windows are! I was wondering if replacing the weather stripping would fix it but maybe not!

  29. Hello, it seems that I am another victim of poorly hung vinyl windows. We also have poorly hung (warped, botch job) vinyl siding on the rear of our masonry built house. This,was done by a flipper who had no integrity nor taste.

    I can live with that but I can’t live with waking up during a rain storm to find water all over the floors leading from the windows.. it’s only where the windows are which leads me to believe that I’ve got a pretty serious issue on my hands.

    We have had a few people come to try to figure out why water is entering the group for floor renta. Apparently it’s coming in behind the siding and windows. The flashing is so poorly done that I can’t imagine I even have a waterproofing membrane behind the siding.

    Thank you for your info and any feedback would be fantastic, we are at a loss:(

  30. Vanessa, send pics to and I will try to help.

  31. During a rain, water gathers in the lower horizontal bottom channel on one of my PVC double-insulated windows. The channel has small outlets on both ends. I poked through the outlet and the water quickly drained. Is this the best that can be done, or is there anything else I should be doing to prevent, or clear, water accumulation in the future? Many thanks for your reply, and for your informative website.

  32. Clearing the weep holes is always good. You can also inspect the weatherstripping to make sure the water entering the system is kept at a minimum.

  33. Hi there

    I love this article so much , i have been learning to it with my every revisit.
    Thanks for sharing.

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Photo of the day

Chemical analysis of nickel sulfide inclusion. In addition to nickel (Ni) and sulfur (S), the glass impurities also include oxygen (O), sodium (Na), silicon (Si), potassium (K) and calcium (Ca). Thanks to Jianjun Yang, Xinyi Glass and South China University of Technology for these images.