How to measure

Almost every remake we see comes from one mistake: someone measured the old frame instead of the hole in the wall. The new frame has to fit the opening, not the thing currently sitting in it.

The method

Width. Brick to brick, or plaster reveal to plaster reveal if the reveals are finished. Measure at the top, the middle and the bottom. Use the smallest of the three. Openings are rarely square and the frame has to pass the tightest point.

Height. From the underside of the lintel down to the cill, threshold or floor level. Again, measure left, centre and right, and take the smallest.

Depth. How thick the wall is at the opening, and where in that depth the frame needs to sit. This matters more than people expect on a cavity wall.

What we do with your number

Give us the opening size. We take the fitting tolerance off ourselves — typically 5–10mm all round so the frame can be packed and levelled. Do not deduct it yourself, or it gets deducted twice and the gap becomes a problem.

Rooflights are different

A lantern or flat rooflight is ordered to the external size of the finished timber kerb. Measure the kerb once it is actually built, not off the drawing. Ten millimetres out on a rooflight is not something you can pack out.

Before you send it

Write down which way the door opens and which side the hinges are on, viewed from outside. Note whether there is a cill already. Photograph the opening. Then send the lot with your enquiry — if something does not add up we will query it before anything is cut.