Measuring up for double glazing.

[tryitandsee]

First time for me fitting windows.
What allowance do you give when measuring width and height.

I have a sash window, will take out the parting beads and leave the frame in, I appreciate opening not always square, but do I have to leave a big enough space to get the plastic frames level. Any tips appreciated.

 

[cmother1]

It's a bit unusual to fit D/G to a sash window sub-frame. The timber is often starting to decay and will always need maintenance in the future.
The company I deal with expects exact opening measurements and makes the windows 10mm smaller in both directions unless told otherwise. As the measurer you would have to take account of an opening that was off-square.
Fitting into an existing subframe is much neater if you have units made with 'odd leg' section UPVC - basically a flange to sit on top of the timber and hide any gaps from the outside. Talk to your supplier about it.

 

[masona]

As it's your first time make a square template for measurement so you know the window will fit, I too go for overall 10mm

 

[tryitandsee]

Thanks to you both.
10mm overall it is then, both width and height


I have seen on some suppliers web-sites, that the frames will expand/contract in our weather conditions, I suppose this is another good reason to make the gap 10mm.

 

[masona]

10mm will covered it but doesn't expand to 10mm, normally 3-4mm, some of them don't expand at all are mostly white frame

 

[The-brickie]

Might want to check the diagonals as well... see how far out (if it is) of square it may be..

 

[masona]

A square template will see to that