Measure from brick to brick, not your window frame sizes.

Make sure you measure your window at the bottom, at the top and at both sides as the size may vary as shown in the diagram above.

Once measured deduct 10mm overall e.g. if your window measures 800mm high by 1000mm wide the new sizes will be 790mm x 990mm.

Measure from brick to brick, not your door frame sizes.

Make sure you measure your door at the bottom, at the top and at both sides as the size may vary as shown in the diagram above.

Once measured deduct 10mm overall e.g. if your door measures 2100mm high by 900mm wide the new sizes will be 2090mm x 890mm.