ROOFING NINJAS
Roof Window Leaking: The Window or the Roof Around It?
Homeowner advice from Roofing Ninjas · 14 September 2026
Water around a roof window does not automatically mean the glass or the whole window has failed. The unit and the way it joins the roof need to be considered together.
Record what you can see safely
Note where the water first appears and whether it follows rain or occurs in other conditions. If a model label is safely accessible from indoors, photograph it. Share existing pictures of the outside, but do not climb onto the roof or lean out to get them. Distinguishing rain entry from internal condensation is part of the assessment.
The flashing needs to suit the arrangement
VELUX provides different flashing products for different installation conditions and roof materials. The actual window, covering and pitch need checking. A generic reference to “new flashing” is less useful than an explanation of the product and arrangement proposed for your roof.
Why the adjoining covering matters
If the roof covering itself is unsuitable for the pitch or has other defects, replacing only the window may leave part of the problem unresolved. Ask what evidence identifies the cause and which surrounding work is included. Equally, do not assume every window concern requires a complete roof replacement.
Discuss it when planning a re-roof
On our Crosby low-pitch extension project, the scope included both the roof covering and roof window replacement. It is an example of considering the two together. If you already plan to replace the roof, tell us whether you want existing roof windows retained or assessed for renewal, including any work to internal finishes that may need separate arrangements.
See the actual work
See the Crosby roof and roof window replacement. View the project photographs and the work recorded for that property.
Technical reference: VELUX: flashing products and installation conditions. The requirements for an individual roof need checking against its actual specification.
Useful next reading
- Can the Wrong Roof Tiles Cause a Low-Pitch Roof to Leak?
- Is It Loft Condensation or a Roof Leak?
- Compare roof replacement quotations
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