What's the rule of thumb for rough opening as compared to the actual size of a window?
How small of a gap would you NOT want?
How about large? Is there is a gap size that is just too much?
Window mfg supply RO measurements when ordering windows. I believe the RO was a half inch wider and taller for our windows. That was for windows with a flange mount.
How close to cut it? Depends on how skilled the builder is at placing the studs plumb vertical and the sill and header level.
I did the half inch and found I could have made it maybe 3/8 with no difficulty. But if something was off then too small a RO could cause problems.
I'd want enough of a gap to make it easy to get the spray can foam into place, but not so wide as to make the nails/screws too close to the wood edge.
I built my rough openings 1/2 in. larger than the window as suggested by the manufacturer, which leaves 1/4 in gap all around. I was pretty careful but somehow some of the windows ended up being a snugger fit than I wanted. In retrospect 1 in. larger opening wouldn't have hurt a thing. Too big is better than the other way around.
Thanks guys. Exactly the info I was looking for.
If your talking vinyl windows what ever the stated size is , that the RO size. Pretty simple , a 3-0' x 5-0' window gets a 36" x 60" RO.
When you get into wood windows Anderson , Loewen , Marvin's etc the company provides the sizes for their window.
Neither. We're going with fiberglass...
Quote from: Erin on March 11, 2011, 12:47:04 PM
Neither. We're going with fiberglass...
Same as vinyl the net RO size matches the size they say it is , they reduce the window by 1/2". So if they say 3-0 X 5-0 , it's a 36"x 60" RO.