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mattcheck 09-15-2013 08:00 PM

Pella double hung vinyl windows bowing
2 Attachment(s)
I had Pella double hung therma star vinyl windows installed from Lowes back in October of 2006. They replaced old wood windows with storm windows. Problem is that now on 4 of the windows the bottoms have bowed up towards the center. I am going to post a picture its kinda hard to tell in the picture. I am wondering what could cause this and if anyone has any suggestion's.

joecaption 09-15-2013 08:34 PM

Someone really messed up on that install.
Let me guess the windows were already wrapped before the replacements went in.
That's backwards.
That looks like poop where the sides of the jambs where not made in two pieces so the window stops would be covered and the coil stock should have been installed over the sill all the way up to the step where it meets the stool so it would be covered and water could not get in under the new window.
To answer your question it sure looks to me like the windows where installed to tight. Someone messed up when they measured them, or possibly to much or the wrong type foam was used. Simple to check, remove the casing to see if there's a gap between the window and the rough opening.
Sure looks like someone also did not go to caulking 101 class on that one.

wkearney99 09-15-2013 08:41 PM

What went in around the windows? What kind of insulation?

Are the sashes any tighter to raise/lower than before?

I kind of wonder what sort of pressure is being exerted against the sides to cause the bottom to buckle upward like that.

Windows on Wash 09-16-2013 05:15 AM

While there is likely some installation failures (just using the finish quality as an indicator) at hand, that window is so flimsy that they can bow over time.

This is why most pros are so vehement about staying away from some of these model windows.

Post a picture of the interior reveals with the window just raised slightly and answer the other questions about operation and we will get you pointed in the right direction.

You aren't going to like the answer regardless if you want to get rid of that bow.

mattcheck 09-16-2013 11:30 AM

The hole process of having the windows installed was a mess. First I had to pay lowes $35 to measure the windows which you get the 35 back when you pay for windows. Have to wait 2 weeks for windows to come in to make sure they all right to make appointment for install. Well they came to install them get half way through and they said half windows were wrong size they had to reorder the ones that were wrong.
I talked to lowes they told me to call pella about windows. I will never have them install anything cause it was such a terrible job all the caulking is bad everything is bad.

mattcheck 09-16-2013 11:46 AM

2 Attachment(s)
I attached interior pics of one of the windows. I know they used spray foam and the window is harder to open than the others also the one in bathroom is almost impossible to close tightly. The windows didn't bow right away they started over the past couple years about 6 years after install.

wkearney99 09-16-2013 12:34 PM

Well, you've got paint out there that's pretty neglected. That'd be the same time for maintaining the caulk too. They don't last forever, they need to be maintained. 7 years is too long.

Any signs of leaks, either inside or outside of the windows showing problems? I ask because there aren't too many ways for what's been an otherwise stable frame to start bowing. Moisture being a possible cause as wood will typically swell when it's gotten wet.

HomeSealed 09-16-2013 01:00 PM

I'm not going to comment specifically on brand, but I see this on a regular basis with lower end windows. It is a flimsy extrusion, particularly at the sill. If the width was too tight at the bottom, it would pinch the window inhibiting operation before it would cause the bowing.
I'm sorry to say mattcheck, but this is EXACTLY what is to be expected in this situation. Cheap product, cheap install = problems a few years down the road.

What to do now? At this point, the only way that the manufacturer will do anything about it is if it was actually causing the window to be inoperable. The only way to get that bow out would be to drive a fastener down through the sill, however I cannot recommend that as it will void the warranty and also introduce a potential pathway for water into your wall. I'm afraid that as long as the window is operating, you can only leave it as-is and recaulk the exterior. The only possibility that I can think of install related that would cause that would be using the wrong type of foam, however given that you stated that this has developed over time, that is unlikely.

Windows on Wash 09-16-2013 05:57 PM


A combination of moisture, bad install, and possibly bad foam.

You could dig out the sealant under the sill and see if it is tight on that section but I highly suspect that the bow is from the pinch on the jamb sides.

Fix'n it 09-17-2013 09:48 AM

i would pull that caulking off and see what is under there. and if nothing is found = gap.
i would push down on the sill, just to see what kind of "give" it has.

hand drive 09-20-2013 11:39 AM

I'm not sure about this but you could possibly raise the little 6" pvc screw covers that sit in the sash guide at the bottom of the sides of the window(outside sash) and adjust the screw that is adjustable. try and get the sash guide (widow jamb) to spread out some to relieve the bowed tension width way along the bottom of the seal. depending which way you turn it the screw will either tighten or loosen against the guide.

also check under the seal extension insert to see where the pressure is coming from, could be the original seal raising but most likely a result of them applying foam underneath during install or installing replacement window tight down onto an already bowed seal...

rossfingal 09-20-2013 01:21 PM

Yeah, I can see a "bow" on the bottom and a bow on the side -
Wrong foam?!?
The windows look like they were already wrapped before they were replaced.
Bad install!
(What do you want from a "Big Box" store!)

Did somebody tell you - "we'll build something together"?!?

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