bowed up

Do it yourself Questions - If Your Bound & Determined
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bowed up

#1 Post by 53jimc » Mon Apr 09, 2012 5:59 pm

Hi All,

I'm new here, from upstate SC.

I'm replacing the windows in my 1954 model brick house. Most of the windows are original and are in really bad shape.

I bought the replacement windows from Home Depot. They seem to be really good windows and I think they'll have a great service life. Hopefully they'll last as long as I do, then it won't be my problem.

This is, imho, a difficult installation. I'm having to do this from the outside, which I have read is a common thing. So, I'm having to trim all of the stops to get the old windows out, then place the new windows in and custom fit outside stops, which I'll cover with coil, to seal off the windows. It's a real pain but worth it.

The problem I'm having is, even though I know I have enough space top to bottom and side to side, and I know the sill is not bowed up, the bottom of the new window bows up. It looks to be a quarter inch higher in the middle than on the sides. I haven't been able to find any place where the window is binding to cause this.

So, my question is: Have any of you had this issue, and if so, what were your solutions? So far I have replaced 6 of 11. 4 of the 6 have this problem.

Thanks in advance for your help.


Delaware Mike
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Re: bowed up

#2 Post by Delaware Mike » Mon Apr 09, 2012 8:16 pm

What brand and series of windows are these? Sounds like a lower-end AC/Silverline product. If you have a sill with a "frown" in the center here's a easy fix. I may slightly shim both corners to level, often it may not be needed if the sill is really level and without any crowning. Try to press the center of the sill to level. If it flattens out (lower sash is raised) with pressure from hands pushing you should be able to correct this.

You will want install all of the anchors first. I would take a 3/8" new forstner bit, or a 3/8" counter sink and carefully drill a precise hole through the center of the sill. Make sure it's only through the top layer of vinyl in the sill. The depth of the hole should be directly center of where the middle of the bottom sash would meet the sill. Once the lower sash is closed the plugged hole would not be visible. I then would take a stainless screw and dip the shaft in some silicone. Next, sink the screw with your drive or by hand with your Phillips screw drive so that the sill comes level completely across and the tension on the locks is acceptable. You will need to plug this hole with a nice factory supplied color matched PVC cap. Most manufacturers send them with the windows, but not all. I prefer ones that have a flat head and not a raised pan head. I make sure that the head of the screw has some extra silicone on it as well as a ton on the plug. Once the plug is fully secured to the sill, I always wipe the excess with some thinner or mineral spirits.

This can void a warranty, so be careful. I would consider since you have frowned sills on brand new windows, to be the lesser of two evils. There are a lot of dirty little tricks that the vinyl guys get good at. I'm not an advocate of drilling into sills, but you have little choice at this point if that frown bothers you and impedes the correct seal or lock function of the window.

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Re: bowed up

#3 Post by HomeSealed » Mon Apr 09, 2012 10:05 pm

DM's advice is on point. That said, this is a great testimonial for why a high quality window should be chosen. There are too many choices out there that offer a flimsy sill design that will inevitably end in frowning.

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Re: bowed up

#4 Post by TheWindowNerd » Thu Apr 12, 2012 7:10 pm

I would agree that this is a product problem.
Though to consider the removal of the exterior stops as difficult is telling also.
Last edited by TheWindowNerd on Sat Apr 14, 2012 7:18 am, edited 1 time in total.

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Re: bowed up

#5 Post by toddinmn » Thu Apr 12, 2012 11:35 pm

You could also return the windows.

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