What sizes should I measure?

What sizes should I measure?

Before ordering your Roof Maker products, it is essential that you understand how to go about measuring for a rooflight, and make sure you have the correct sizes.


The general process for measuring for a rooflight is described below. However, there are additional considerations for certain products. These are explained underneath.

  • The measurement we work from is the size of the internal hole — so measure the size of the hole you want to create and we’ll make a rooflight to fit
  • If you want to leave the black aluminium frame showing, you should include finish plasterboard. If not, give us the size of the hole before plastering.
  • Rooflights are designed using a 70mm wide aluminium kerb detail profile, which can sit on a minimum 70mm wide x 25mm deep timber frame.

Fixed flat rooflight

This can be supplied as a modular product, which joins together in modules of 2000mm x 1200mm. This will allow sizes of up to 10,000mm x 1200mm or 10,000mm x 2000mm.

O-lite round rooflight

The maximum size we currently offer for this rooflight is 1500mm.

Pitched roof windows

If you are ordering the hinged version of our Luxlite rooflight, make sure you allow an additional 130mm between your rafters for the rooflight to fit into.

Sliding rooflights

TIP: Bear in mind that a sliding window will also need an equivalent space to one side of it, so it has space to slide open safely. You do not need to include this in your measurement when ordering.

For more information, talk to our rooflight experts

We hope that you found this guide useful and informative. Don’t forget, we always here to assist, so if you require further advice on measuring for a rooflight, or if you need help choosing, please call 0116 269 6297 to speak to one of our experts.