Timber Frames:
Firstly you must locate where the beading of the frame starts and in doors & side screens this is usually internally and should be where the flat part of the frame/opener finishes and starts to shape in towards the glass. To measure the opening of the frame (thight sizes) you would measure from A to B for the width and in this instance lets say that A to B is 615mm. You then need yo measure the height of the opening. This measurement is taken from C to D (D is not shown in the photo but it is the opposite of C).
We now have a measurement of 615 x 1023 but this is not the accurate glass size because this is the thightb size (see below). We need to deduct a small amount so that the glass can be positioned correctly and also compensate for any inaccurate measuring by glass cuuters. A common amount to deduct in wooden frames is 5mm and this measurement needs to be deducted from the width and also from the height therefore the accurate glass size for this frame would be 610mm x 1018mm.
As an industry standard the width is always stated first when supply glass sizes.
PVC Frames:
Firstly you muat locate where the beading of the frame starts and this is usally where the flat part of the frame/opener finishes and starts to shape in towards the glass/ With PVCu frames the beading isn't always on the internel side of the frame, it may be an externally beaded frame so check both sides.
Above you can see the red arrows A,B & C pointing to the area where the PVCu beading slots into the PVCu frame. To measure the opening of the PVCu frame you would measure from A to B for the width and in this instance lets say that A to B is 455mm wide. You then need to measure the height of the opening. This measurement is taken from C to D (D is not shown in the photo but is the opposite of C) Lets say that the measurement of C to D is 994mm in height.
We now have a measuremnet of 455 x 994 but this is not the acuurate
glass size because we need to deduct an amount so that the glass can be postioned correctly and also compensate fot any inaccuratae measuring by the glass cutters and any imperfections made during the double glazed sealing process. A common amount to deduct in PVCu frames is 10mm and this measurement needs to be deducted from the width and also the height therefore the correct glass size for the would be 445mm x 984mm