How to Measure for Your Composite Door
This guide is intended to assist experienced tradespeople or confident DIYers in measuring accurately.
Please note: we do not accept liability for incorrect measurements or surveys.
How to Measure for Your New Door
What You’re Measuring
You’ll need to measure the full width and height of the opening — that includes the frame and cill (not just the door slab).
Width
Measure across the top, middle, and bottom of the opening. Take the smallest of the three and subtract 10mm to allow for fitting clearance.
Height
Do the same vertically: measure on the left, centre, and right. Again, use the smallest measurement and deduct 10mm.
Check It’s Square
Measure the diagonals (corner to corner). If the two diagonal measurements differ by more than 5mm, the opening may not be square and could require adjustment.