How to waterproof a rooflight
[edit] Introduction
There are many reasons why a rooflight might start leaking. It could be the result of an inadequate installation, or the rooflight may have been damaged after being exposed to high winds or suffering an impact. In some cases, a leak can even turn out to be not a leak at all, but a condensation problem.
Even a small leak can be a source of inconvenience for a building’s occupants, and it could damage expensive equipment or decorations. Problems such as damp and mould can also result from a leaking rooflight, leading to uncomfortable conditions and potential health hazards.
[edit] Methods for waterproofing rooflights
As with any type of building penetration, there are several ways to waterproof a rooflight, and the right choice will depend on the roof construction, as well as the finished appearance that you wish to achieve.
In residential buildings with pitched roofs, for example, rrooflight installations are typically sealed using flashings with tiles layered carefully over the top for a weatherproof finish.
However, this method will not work on most commercial buildings – particularly those with flat or low-pitched roofs and no roof tiles. So other techniques will be required. Although a waterproof rooflight can be achieved with materials such as EPDM rubber, or even traditional roofing felt, GRP is one of the best ways to ensure a leak-free result that will look good and last for many years with minimal maintenance.
[edit] Related articles on Designing Buildings
Featured articles and news
Apprenticeships and the responsibility we share
Perspectives from the CIOB President as National Apprentice Week comes to a close.
The first line of defence against rain, wind and snow.
Building Safety recap January, 2026
What we missed at the end of last year, and at the start of this...
National Apprenticeship Week 2026, 9-15 Feb
Shining a light on the positive impacts for businesses, their apprentices and the wider economy alike.
Applications and benefits of acoustic flooring
From commercial to retail.
From solid to sprung and ribbed to raised.
Strengthening industry collaboration in Hong Kong
Hong Kong Institute of Construction and The Chartered Institute of Building sign Memorandum of Understanding.
A detailed description from the experts at Cornish Lime.
IHBC planning for growth with corporate plan development
Grow with the Institute by volunteering and CP25 consultation.
Connecting ambition and action for designers and specifiers.
Electrical skills gap deepens as apprenticeship starts fall despite surging demand says ECA.
Built environment bodies deepen joint action on EDI
B.E.Inclusive initiative agree next phase of joint equity, diversity and inclusion (EDI) action plan.
Recognising culture as key to sustainable economic growth
Creative UK Provocation paper: Culture as Growth Infrastructure.
Futurebuild and UK Construction Week London Unite
Creating the UK’s Built Environment Super Event and over 25 other key partnerships.
Welsh and Scottish 2026 elections
Manifestos for the built environment for upcoming same May day elections.
Advancing BIM education with a competency framework
“We don’t need people who can just draw in 3D. We need people who can think in data.”