Looking for advice and past experience.
A customer called to show me their vinyl windows. On the south side with full sun exposure the window frames are bowed out. The worst frame is out 1 3/8 inches from straight in 36 in of window width. Naturally the window does not close completely. Surprisingly, the glass is not (yet) broken.
Construction is wood frame/brick facing.
My guess is the cause is thermal expansion. The coefficient of thermal expansion for PVC 10 X that of steel: about 3 X 10-5 in/in oF vs steel about 7 X 10-6 in/in oF.
Owner recently purchased the house “as is”, so it is their problem. Owner wants me to remove window, straighten it and replace it in the same opening (enlarged if necessary). House is about 5 years old.
This solution does not make sense to me. I think the PVC, having bent once is now weakened and more likely to bow out next summer.
Any experience with 100%vinyl frames to share? Is this a manufacturing issue in that the fastening means for vinyl windows do not allow for sufficient expansion? Or an installation issue? Will these frames stay straight?
anwalt
Replies
Are these new construction windows (nail fins) or replacements?
I would bet on a poor installation. New constructon vinyl windows can't be "pinched" in the rough opening and they MUST be nailed off according to the manufacturers directions - roofing nails in the slots only and don't drive them tight.
You'll have to open things up to know for sure and I wouldn't bet on being able to straighten them.
Last year, I replaced a double pane kitchen garden window that had been installed with sheetrock screws driven tight in every slot. It was a southern exposure and I was amazed that it had lasted as long (10 yrs) as it had. No glass had broken but the seals were long gone.
I have not opened the trim, so I cannot state as fact, but the house is about 5 years old, so I assume new construction windows. I see no screws through the frame.
You wouldn't see any screws thru the frame - they would be in the nailing fin behind the exterior trim.
If this were me, I would offer to remove the exterior trim (hopefully without destroying it) and see if you can identify the problem. Leave the window in place for now. Take lots of pictures and post them on here. Several of us have lots of window experience and may be able to help you out.
Someone else mentioned expanding foam as a porential cause and that's certainly possible. You should only use low expansion foam around windows and doors - the high expansion stuff creates way too much pressure and can distort the framework. Home Depot sells theirs as "Window and Door" foam.
"Owner wants me to remove window, straighten it and replace it in the same opening (enlarged if necessary)."
I would never touch that in a million years. How can you fix a vinyl window that has bowed that much? Your not a window manufacturer. Also how can you guarantee that it will work? What happens if you brake it? No matter who's fault it is/was it's not your job to fix it unless you own the company who made them.
One possible cause is Great Stuff used to foam around the rough opening.
happy?
Dan,
A good thought ! !
anwalt
Id guess that the brick is mortared tight to the bottom of the window. As the wood frame shrinks drys and settles the windows want to move but the brick won't let them. Rarely do I see windows installed in brick correctly. Second and third story windows will show problems worse then first floor.
If this is the case the only correct way to solve the problem is remove the brick sill, cut the brick and relay them leaving 3/8 to 1/2" gap between window and brick. Since these are vinyl they may be straightened. I see this all the time on Andersen and since they are wood, and the pressure crushes the wood they are not salvageable.
Along with relieving the brick to window pressure it's worth a check to make sure squash blocks are in place.
As Sledge sez....sounds like the windows are brick bound. In a masonry installation the window should have a 1/2" space at the bottom and 1/4" on the other three sides. As the framing shrinks and settles the frame of the window gets 'hung' on the bricks, which distorts the frame.Curious, are there any windows, not in brick, with the same symptoms?View Image