Bow window support

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bigshopper
Posts: 5
Joined: Sat Apr 02, 2005 10:31 am
Location: Wisconsin

Bow window support

#1 Post by bigshopper »

I am getting quotes for a 5 panel bow window installation. 1/2 the contractors claim bottom support is best and the others claim top hanging support is the best. Any opinions?

P.S. I'm almost settled on VinylView windows. Any last thoughts?

Window4U (IL)
Posts: 1548
Joined: Thu Oct 07, 2004 8:46 am
Location: Sales and Installation in Chicagoland and Central Illinois

#2 Post by Window4U (IL) »

Either support method will work depending on a couple of factors.
Many homes do not have adequate suport underneath the window to simply put support brackets onto the wall without taking the siding off and adding support where the brackets need to be. For example, I run into a lot of homes in certain subdivisions where the exterior sheathing is celotex or styrofoam, and then vinyl siding was installed over the top. In this situation, without taking the siding off and adding adequate framing underneath, the brackets won't hold and the window will definitely sag.
Plywood sheathing is not much better to attach to unless it is very stiff. If it gives even a little, the window will sag. There is always the chance the studs are exactly where you need them to be behind the plywood, but that's not likely.

With the hanging method, installation is key. Many of the hardware packages that are used are just cables that the installer winds through a cleat. I don't care for this type because they don't have a way to adjust the tension to raise the window to level. When I have used these in the past, I've used a jack under the window to raise it and then attached the cable. I prefer the hanging kits that utilize a turnbuckle so that it can easily be raised to level.
If I'm not completely sure of the strength of the rafters, sometimes I will sister lumber to the existing rafters to make them stronger and/or lag bolt a 2x6 across several rafter tails to evenly distribute the weight, especially if it's a big window with a large projection.

Lastly, there are cases where no support is needed. Some windows have very small projections (past the exterior wall edge), but deep wall depths such as on brick homes. You can very often get enough support under the window that the few inches it sticks out is not enough to need any extra support.

bigshopper
Posts: 5
Joined: Sat Apr 02, 2005 10:31 am
Location: Wisconsin

#3 Post by bigshopper »

Thanks for the reply. I guess I should have given more information on the structure. Its a frame house built in the late 50's. It has about 1 1/2' of over hang above. Im not worried about the siding as we are having the window downsized and they are already going to have to patch.
The current window is 103 X 62 and we are raising the bottom so the height will only be 52.
I guess based on that they can do either and that is why I was asking which method is better. One contrator said it puts unnecessary weight on the rafters..the other said you are only supporting a couple of spots underneath and the window will sag or go out of level.

I am actaully thinking of putting both in.

Thanks again

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