Roof lanterns usually leak because of installation faults, not the glass itself. The most common causes are failed seals or joints, a poorly waterproofed upstand, misaligned glazing bars and bad drainage around the kerb. What looks like a leak is often condensation.
What are the most common causes of a leaking lantern?
- Worn or poorly applied seals and glazing joints
- An upstand that is too low, or a waterproof membrane not carried up the sides and sealed (around 150 mm is the usual minimum upstand)
- Misaligned panels or glazing bars that open gaps in heavy rain
- Roof falls or gutters that let water pond around the kerb
Is it a leak or condensation?
Dripping from the inner pane on cold mornings points to condensation, not a leak. It suggests moisture in the room or a poor seal on the inner unit. A leak shows up during or after rain, usually at the kerb or glazing bars.
How are lantern leaks fixed?
A water test finds the source. Repairs range from resealing joints to re-dressing the flashing and membrane at the upstand. A lantern that leaks again after resealing often has a kerb or roof-fall problem, so the surrounding roof needs inspecting.
Wednesfield Trade Windows is a family-run, Certass registered installer, and the survey confirms what needs sign-off on your property. See our roof lanterns for more detail.
Thinking about a roof lantern? We supply and fit lantern roofs across Wolverhampton and the surrounding area, and you deal directly with us, the owners. Call 01902 633355, message us on WhatsApp, or request a quote.