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swclark70

Problem with my new replacement windows

swclark70
9 years ago

Hi all. I'm new to this site and wonder if any of you have any experience with this problem.

We recently replaced all of our original wooden Pella windows (house was built in '85) with new Okna 500 replacement windows. The installation went well, but there was a hitch. After removing the old Pellas, the installers noticed that the existing frames had aluminum sills that weren't merely flat, they actually flange up toward the interior window (perhaps to prevent water from running towards the inside of the house). This created a larger than normal gap between the old frames and the new windows, which our installers spent an extra day filling with 1/4" wood trim and caulking. The end result looks good.

But, now on to the problem: Within a week, it got real cold (windows were installed December 10th, I think), and the window frames started to frost up at the very bottom (see picture below) where the new windows met the old wood frame. It was all well insulated under the new windows, but our installers think that it must be the unusually shaped aluminum sills that are conducting the cold up to that part of the window (which wouldn't be the case if the aluminum part was flat and not flanged up). They were not able to remove the aluminum when installing, as the saws would not have reached in the far corners. (Note: in the picture below, the area above the frost is the new window; the area below the frost is painted wood, which was part of the original window's frame)

To fix the problem, they put exterior caulk (heavier than what they originally did) on the insides, in the hope that it would create enough of a barrier between the inside and the aluminum flange. But as of this morning, when it was zero degrees out, the frost is back with a vengeance.

Has anyone seen this weird aluminum sill when replacing wooden Pella windows circa mid-1980s? Our installers have never seen it, despite many years of experience. And now I'm not sure what can be done to fix the problem, short of removing the windows and somehow taking that aluminum out.

Thanks in advance for any thoughts you can provide. My one thought was to have the window guys call Pella and see what advice they might have, as they're the ones who designed that aluminum sill.

Comments (23)

  • PRO
    Windows on Washington Ltd
    9 years ago

    Did they spray foam around the perimeter during the installation?

  • swclark70
    Original Author
    9 years ago

    I wasn't there during the installation (my wife was), but the installers told me they did insulate well underneath the window. I don't know if it was spray foam or not, though. I can ask them.

  • PRO
    Joseph Corlett, LLC
    9 years ago

    swclark70:

    This is your window installer's problem. I promise if they have to reinstall each window and remove the aluminum, they'll never do this again. I've paid a lot of tuition myself, so it doesn't bother to watch others do the same.

  • PRO
    Windows on Washington Ltd
    9 years ago

    If the aluminum is thermally bridged to the exterior, this will continue to happen.

    If the insulation that was put in was fiberglass and not spray foam, this will continue to happen.

    You have to address the thermal conductance of the aluminum.

  • swclark70
    Original Author
    9 years ago

    Thanks, w.o.w. I think it was fiberglass insulation and not spray foam. So will spraying the foam insulation around the exterior side of the aluminum stop the thermal conductance? Do you think this can be done without having to remove the windows?

  • PRO
    Windows on Washington Ltd
    9 years ago

    Shouldn't have to remove the windows but they will have to rip off the capping and remake that portion. That is not a bit deal.

    Should have been spray foamed.

    Fiberglass is worthless in this application.

  • mmarse1
    9 years ago

    this can be done from the outside using spray foam without removing the windows.
    even with spray foam, condensation can still occur due to metal being so darn conductive. it will help though.
    be thankful you don't have a surface 4 hard coat low E coating.

  • swclark70
    Original Author
    9 years ago

    Thanks, guys. My window guys are looking into a game plan. I suggested what you both said above.

    My wife says she did see the guys using spray foam insulation, but on the sides of the windows. She wasn't watching when they did the bottoms to see if it was used there. I can't imagine why they'd do the sides but not the bottom, though.

  • HomeSealed_WI
    9 years ago

    The sills need to be done from the exterior. The top and sides can be either/or depending on whether they did an interior or exterior stop removal. That could be why she didn't see the bottom.

    So is that surface where the frost is metal?... Or is the metal part the little lip that is a step down?

  • swclark70
    Original Author
    9 years ago

    The surface where the frost is accumulating is where the bottom of the new window is touching the existing wooden frame. I'm not sure if that part of the window is metal or not -- it kind of feels like it. But the aluminum part that the window sits on is below that point somewhere, perhaps touching the window very close to where the frost is accumulating.

    Last I heard from my window guys, they're calling okna for their thoughts.

  • PRO
    Windows on Washington Ltd
    9 years ago

    This is not a product issue.

    This is an install issue.

    Tell them to pull the capping and spray foam it.

  • HomeSealed
    9 years ago

    Okay. So the window is set in an old pella aluminum clad frame. The interface showing frost is where the new vinyl frame sits against a wood section of the old window. This looks to me like a failure to seal around the perimeter of the new window as it sits in the old frame, primarily air leakage. Getting that foamed should fix the problem.
    Okna won't have anything to say on this as its an installation issue, not the window.

  • swclark70
    Original Author
    9 years ago

    They just indicated they're going to take out the bottom caps and try rigid insulation (instead of spray foam). I assume because that's cheaper than spray foam? But if air leakage is the problem, it seems like foam is the way to go.

    They're going to try this on one window to see if it works before doing it to all of the windows. I'm going to lobby for the spray foam insulation.

  • PRO
    Windows on Washington Ltd
    9 years ago

    Spray foam the bottom and be done with it.

    I am not sure why this is being made this difficult.

  • HomeSealed
    9 years ago

    Rigid foam, lol. That's a first.
    As wow said, spray and be done

  • swclark70
    Original Author
    9 years ago

    Thanks, guys. They said they'd like to try the rigid insulation because they did already use spray foam insulation in there. But if there's room for rigid foam, seems like there'd have to be room for more spray foam instead.

    On a related note, I just noticed that my patio door track height at the bottom seems very high. It's about 3" off the hardwood floor. Is this typical, or out of the ordinary? The door it replaced was not this high, maybe 1-1/2". See the new picture. Thanks again!

  • HomeSealed
    9 years ago

    Nothing out of the ordinary about the patio door sill, some are just taller than others, and installation circumstances can cause that to vary by an inch or so as well.
    On the foam board, I still don't get that, but whatever. As long as they fix and seal it.

  • swclark70
    Original Author
    9 years ago

    They are going to test out the foam board on one window to see if that solves the problem (before doing all windows). I'm going to ask if they can do a second window with the foam spray as long as they're coming out here. I can then compare the two and see which is a more effective solution. I'll even have a can of the spray foam ready for them.

    Thanks again. Re the patio door sill, I figure I can just put a thick rug right at the entryway to reduce the height difference slightly.

  • PRO
    Windows on Washington Ltd
    9 years ago

    Keep us posted how it turns out.

  • HomeSealed_WI
    9 years ago

    +1... I suspect that they either missed foaming some sills or there are some significant gaps in the foam. No other reason that should happen.

  • swclark70
    Original Author
    9 years ago

    FYI, one of the installers came out today and sprayed foam insulation at the bottoms of two of my windows (to test this approach before doing all of them). On one of them, he took off the bottom cap and sprayed, then put it back and recaulked. On the other one, he left the cap on and sprayed the foam in through about six or seven drilled holes (at the caulk line), every five inches or so. He then removed the excess, although after an hour there's still a bit oozing out. That'll be broken off later and recaulked at the holes.

    I'll now wait for super cold temps again and see if these windows have any frosting on the inside, and whether one approach works better than the other.

    I'll keep you posted.

  • PRO
    Windows on Washington Ltd
    9 years ago

    Sounds good.

    That should do the trick.

  • HomeSealed_WI
    9 years ago

    Slightly skeptical about the drilling of the holes method as you can't see if you are getting full coverage, but ultimately the proof will be in the pudding. If it fixes the problem that is what matters.

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