Replacing picture windows

[captcolby]

I want to replace a couple small picture windows and a couple large picture windows in my house. I don't know where to take the measurements to get them ordered. I know that the measurements are the most important thing. Can anyone help me with this?

Thanks

 

[Nestor_Kelebay]

Captain Colby:

Normally window companies prefer to come out and take their own measurements. Typically customers won't know how much space to provide around the window, and that can end up causing problems if the window isn't properly sized for the opening. Better to let the window company take the measurements even if you want to install it yourself.

 

[captcolby]

Nestor,

Thanks for the reply. I am planning on doing the replacement myself. I live 120 miles from the closest window company, so that is a major problem. So I am hoping for a little help.

Thanks

 

[Nestor_Kelebay]

OK, when you say you want to replace "picture windows", what exactly do you mean by that term?

My understanding of a "picture window" is a window that can't be opened. That is, just a sealed unit or even a single pane of glass fitted into an opening and surrounded by window stop moldings on both sides.

Is that also what you mean, or do you mean an entire window assembly, including the surrounding frame, opening hardware and screen(s)?

 

[captcolby]

Yes you are correct. It is the type of window that can't be opened. The house was built in the 50's but I think the windows were replaced in the early 80's. I would like to get something similar, but that is more energy efficient. I will attach some photos soon.

Thanks again

 

[Nestor_Kelebay]

Let me phone up the Carpentry instructor at Red River College in Winnipeg. I know that when they measure window openings, they measure across the top, middle and bottom, and use the smallest dimension. Similarily, they measure height on the left side, right side and middle and, again, use the smallest dimension. And, since the bottom of the window frame is sloped downward to allow for rain water drainage off the sill, all of these dimensions need to be taken in the plane where the inside surface of the glass will be. And, once you have the height and width of the opening, you need to allow for 1/8 to 3/16 of space all around the glass within that opening, so you'd deduct 1/4 inch from both dimensions to get the glass size.

But, I also know that they measure the diagonals because the opening may not be rectangular. It may be a parallelogram like the one shown below. This is the kind of shape you get if you have settling in your house and one side of a wall settles more than the other. (The preceding height and width measurements won't distinguish between a rectangle and a parallelogram, but the diagonal measurements will.)

But, what they do with the diagonal dimensions is something I don't know. There has to be a rule of thumb by which the height and width of the glass is reduced because of any measured difference in the diagonals.

I feel a bit embarrassed here. I always install sealed units myself in my own building, but the window company always comes out to measure the opening. So, I'm much more knowledgable about installing the sealed unit in the opening once you've got it in the back seat of your car.

Lemme phone Red River College School of Carpentry and find out exactly what they do with the diagonal dimensions once they know them.

 

[Nestor_Kelebay]

Captain Colby:

There is no rule of thumb by which to reduce the glass size based on a difference in the measured diagonals.

If you have a wood frame in the rough opening of a stud wall, then the procedure is to remove the window casing around the window (and the caulk around the wood frame on the outside) and simply "square up" the frame by prying with a bar or driving more shims in between the frame and the studs in one corner or the other. That is, you simply pry the existing window frame back into shape so that the diagonals are equal.

In my case, the only picture windows I have are in my front and back lobbies where they consist of sealed units installed in a lattice of painted 2X6's. In that case, there are no separate window frames involved, so it's not possible to "square up" the frames. In a case like that, if the measured diagonals are out of whack, the proper procedure is to either:

1. make a "glass" pane or sealed unit out of a cheap material like 3/8 inch particle board according to the measured width and height, see how it fits the opening. Cut it down until it fits well and order the glass accordingly, or

2. go according to the shorter diagonal. That is, reduce the measured width and height equally so the sum of the squares of the reduced width and height dimensions equals the square of the shorter diagonal.

However, if you still have glass and stop moldings in the existing frame, a relatively fool proof method is also to simply measure the height and width of the exposed area of glass and add 3/4 inch to both dimensions. This presumes there is 3/8 of glass behind the stop moldings all around the window.

Also, "Frank", the owner of Fort Rouge Glass here in Winnipeg, felt that the 1/8 to 3/16 spacing around the glass was too tight and wouldn't leave enough wiggle room. He felt it would be better to count on 1/4 inch of space all around the glass.

So there you have it. There is no real science to the measuring. You simply measure height and width in three places each, subtrace 1/4 inch all the way around for air space, and then measure the diagonals to see if your frame is "square". If the diagonals are the same, you order your glass. If they're different, then you either order the glass based on the smaller diagonal, or make a particle board window and see how well it fits.