Who this guide is for
- Homeowners adding a skylight or roof window
- People concerned about leaks at a roof opening
- Anyone comparing skylight installers
- Owners adding light to a loft or top floor
Probe flashing and weatherproofing
The flashing around a skylight is what keeps water out, so it must match the roof and be installed correctly. Ask how they flash and weatherproof the opening for your roof type.
Flashing is the single most important detail to get right.
- Ask how the opening is flashed
- Confirm flashing suits your roof type
- Discuss how water is kept out
- Treat vague answers as a concern
Check leak-history references
Because leaks show over time, ask to see skylights they installed some time ago and whether they have stayed dry. A history of watertight installs is the reassurance you want.
A fresh install looks fine; how it weathers tells the real story.
Confirm finishing inside and out
A skylight install has an exterior weatherproofing side and an interior finishing side — the reveal, plaster and trim. Ask who handles each and how the inside is finished.
Confirm responsibility for both sides of the opening.
- Ask who finishes the interior reveal
- Confirm exterior weatherproofing
- Discuss trim and plaster
- Clarify responsibility for both sides
Match experience to your roof
Different roofs — pitched, flat, tiled, slated — need different approaches. Confirm the installer has done skylights on a roof like yours and understands the demands.
Roof type drives the whole approach.
Brief and compare on the same scope
Give each installer the same information about your roof and the skylight you want so quotes compare. Ask what could change once the roof is opened up.
Ask to see relevant insurance and roof experience.
- Share the same roof details with each
- Compare on like-for-like scope
- Ask what could change once opened
- Confirm insurance and roof experience
Hiring checklist
- 1Decide the skylight type and location
- 2Ask how the opening is flashed
- 3Confirm flashing suits your roof type
- 4Ask to see older skylights and how they held up
- 5Confirm who finishes the interior reveal
- 6Confirm exterior weatherproofing
- 7Match experience to your roof
- 8Give each installer the same brief
- 9Ask what could change once the roof is opened
- 10Confirm insurance and roof experience
Common mistakes to avoid
- Underestimating the flashing and weatherproofing
- Judging only fresh installs, not how they age
- Leaving interior finishing responsibility unclear
- Hiring an installer unfamiliar with your roof type
- Comparing quotes that cover different scopes
- Skipping insurance and roof-experience checks
When to involve a professional
- Keep cutting and flashing a roof with experienced, qualified professionals
- Confirm flashing matches your roof type
- Ask to see skylights that have stayed watertight
- Ask to see relevant insurance for roof work
- Remember roof and skylight requirements vary by location and project
Frequently asked questions
Questions readers ask about this topic
Why is flashing so important on a skylight?
The flashing around a skylight is what keeps water out, so it must match the roof and be installed correctly. It is the single most important detail, so ask how the installer flashes and weatherproofs the opening for your roof type.
How do I know a skylight will not leak?
Ask to see skylights they installed some time ago and whether they have stayed dry, because leaks show over time. A fresh install looks fine, so how it weathers tells the real story.
Who finishes the inside?
A skylight has an exterior weatherproofing side and an interior side — the reveal, plaster and trim. Ask who handles each and how the inside is finished, and clarify responsibility for both sides of the opening.
Does my roof type matter?
Yes — pitched, flat, tiled and slated roofs need different approaches and flashing. Confirm the installer has done skylights on a roof like yours, and remember roof work requirements vary by location and project.
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