Measuring the aperture

The width and height of your bifold door is the structural opening size minus a fitting tolerance.

We recommend you allow a 10 - 15mm fitting tolerance between manufacturing sizes and the smallest width and height dimension (please see images).

Use a large spirit level and measure the cross corners of the aperture to ensure the opening is square and true.

Take three width and three height measurements and minus 10mm from the smallest to determine the actual required manufacturing size of your door.