Installing windows in an out-of-plumb wall
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| Posted in Green Building Techniques on
I’m trying to decide how to install windows — nail flange or block frame — in a wall that is out of plumb. The windows should be installed to be true in the vertical plane so that they work well, of course, but doing that means that the bottom of some windows would be as much as 1″ out of plane from the top. The walls slope outward so it’s the bottom that would need to be shimmed or padded.
Has anyone dealt with this problem successfully? The way the house has been remodeled means that correcting the slope of the walls is not an option.
Thanks.
Jonathan
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Replies
Jonathan,
It's a judgment call; I've seen replacement windows installed both ways. The windows will function better if they are plumb, but they may look better if they are parallel to the wall.
Choose replacement windows without any flanges for this application. Install them as "in-betweenies" (not innies or outies) and adjust the jamb extensions, inside and out, to trim the opening.
Martin, thanks for the advice and quick reply. I've not installed windows that way before, so I'll do some research and report back here with my plan.
Rule of thumb when remodeling and leaving existing walls as is...
Most of the time minor deviations are set so they "look right" as long as all will function. If function is lost then one would correct the wall etc.
So without seeing your situation, I would follow the wall if not correcting the wall.
The other option often used is... drum rolll... to "split the difference."
My advice, install them flat but don't worry too much about plumb.
Agree with Michael 100%. Align 'em with the wall. If the wall ever chooses to straighten itself out the window will go with.
One of the reasons one plumbs a window is to ensure that both vertical rails are in the same plane. I would investigate to make sure both sides of the aperture are the same plane or once the window is installed it will be twisted and may not close properly. This is easy when everything is vertical, but requires a little ingenuity when not [for instance taping a shim to the level to make it read the wall plumb]
Thanks everyone. I think it's unlikely that the wall will straighten itself out.
I've drawn up a section (and made a partial 3d model) of how I'm thinking of handling this detail. I feel like if I'm going to go to the work of hanging the windows plumb I might as well bring the siding to plumb as well. Rather than mess with shims over foam (Fine Homebuilding's project house video noted some issues with the foam compressing) I am thinking of using shim screws so that the furring strips can easily be brought out to plumb by hanging a plumb bob from the top of the wall.
Here are a few drawings of the detail based on the REMOTE wall system details.
The slope is exaggerated in these drawings so it's visible. I've attached a PDF, which everyone should be able to read, plus the Layout and Sketchup drawings in case those are helpful or you are feeling inspired to improve this detail.
Sill Detail [PDF]
Sill Detail [Google Layout 8]
Sill Detail [Google Sketchup 8 model]