Roof lanterns: sizing, upstands and regulations
How to size a roof lantern and build the upstand it sits on.
How is a lantern sized?
By the external size of the finished upstand (kerb) it sits on, measured once the roof covering is turned up.
How high should the upstand be?
High enough to keep water away from the lantern seal, commonly at least 150mm above the finished roof surface. Follow the lantern system instructions.
Do lanterns need building regulations approval?
In a new extension, the lantern is part of the extension's approval. A replacement should meet the thermal values for rooflights.
Solar gain
South-facing lanterns can overheat rooms. Consider solar-control glass.
This guide is general information for trade customers. The person carrying out the work remains responsible for meeting the building regulations and any planning requirements for the specific job.