Placement for Flanged Window in Rough Opening
Hello,
When installing a new window in rough opening, what is the goal with the gaps? I know this is obvious, but I want to double check how the rough opening extra area is handled in relation to placing the window. Don’t laugh, just making sure I get the most basic idea down
So the rough opening is greater than the flanged window. The flanges however make up ]past the rough opening and are nailed to the window framing. Got that.
When it comes time to place the window (nail flange window), the excess side width in the rough opening should be equal on both sides, yes?
On the bottom, you’re only using the excess space to set the shims where they need to be to make the entire window straight, level, plum, and sliding functional? So anything greater than what the shims eat at the bottom, is 100% left as extra gap at the top of the rough opening to be insulated by whatever is used (spray foam, backer rod, etc)?
That sound correct?
Obvious, I know. Just want to check. Getting ready to set 4 windows for the first time.
Thank you!
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Replies
What's really important is that the window be level, plumb, not racked or skewed, and even with the other windows in line with it. The space is there to give you leeway. When the house is finished the framing will be hidden, all you'll see is the window. Focus on what's visible.
> When it comes time to place the window (nail flange window), the excess side width in the rough opening should be equal on both sides, yes?
Not necessarily. Sometimes you're trying to hit a specific feature symmetry on the exterior or interior. Adjustability helps you do that.
> On the bottom, you’re only using the excess space to set the shims where they need to be to make the entire window straight, level, plum, and sliding functional? So anything greater than what the shims eat at the bottom, is 100% left as extra gap at the top of the rough opening to be insulated by whatever is used (spray foam, backer rod, etc)?
Same deal. Often window heads need to line up across an entire house, so you might want a control line that helps keep things consistent between all the windows, even if the individual ROs are not perfect.
Thank you both. Both very good points.
I hadn't even considered measuring the two windows on the same wall to be aligned perfectly together. Duh. Obviously, but totally would have messed that up. Thanks!
Many contractors let the window sit directly on the rough sill (or sill pan, if there is one) but I, and every window manufacturer I'm aware of, prefer to use "set blocks" under the window. Ideally the gap would be equal all the way around but usually some adjustments are needed, and they don't perceptibly affect performance.
Thank you all very much!