Guide for measuring your Sliding Sash Windows
How to measure for replacement vertical sliding sash windows
Measuring a sliding sash window correctly is actually quite straightforward, but please remember the old builder’s maxim ‘measure twice, cut once’.
Step 1: Measure the depth of the existing sash box. Measuring from the outside to the inside (see picture ).
Step 2: Measure the width of the outside opening in three places; at the bottom, middle and top of the opening, the measurements should be the same but if they are notably different then check to see if there is a visible reason why; this could be because one or more bricks are uneven and the majority of the opening is the same width. You should use the measurement which is most likely to be the original outside width. If unsure, then use the measurement from the narrowest point and minus 10mm.
Step 3: Measure the height of the outside opening in three places; at the left and right side of the opening. If your measurements differ significantly check to see if there is visible uneven bricks or slight subsidence. You should use the measurement which is most likely to be the original outside opening height. If unsure, then use the measurement from the narrowest point and minus 10mm.
Some important points to remember
Measure from outside, brickwork to brickwork. (plaster to plaster)
If that is not possible, measure your existing window.
Measure in a few different positions, take your smallest size and deduct approximately 10mm.
If in doubt, just ask!
If you need any further help, why not take a few photos and email them to us for specific advice.
Please note: We are unable to accept responsibility for incorrect measurements. If you are unsure we recommend that you consult a professional installer/builder.