Lee FlecknellEmergency roof repairs, rental property · August 2026
Highly recommend this company carried out some emergency roof repairs on one of my properties would use again.
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Skylights and roof windows
Skylight installation and roof windows in Welwyn Garden City
Skylight installation in Welwyn Garden City and across Hertfordshire and Northamptonshire, from a family-run roofing company that fits, replaces and reseals roof windows. You get a free survey and a fixed written price before we start, and a leak round an existing skylight is traced to its cause and fixed.
A roof window is the one place where a hole is cut through the roof on purpose, so it is the first place to check when a stain appears on the ceiling beneath it. The glass is rarely the problem. Water gets in round the frame: a flashing kit that has lifted or was never fitted properly, tiles cut too short at the sides, a blocked gutter at the head of the window holding leaves and rain, or seals that have perished after years of sun.
Fitting a skylight is roofing work, not joinery. We open the roof, trim the rafters to frame the opening, fix the window in with its flashing kit, lap the membrane into the window collar and tile or slate back round it so the courses line up. Replacing an old roof window follows the same steps: the old frame and flashings come out, the opening is checked for rot, and the new window goes in with a new flashing kit rather than the old one reused.
The best time to add a roof window is while the roof is open. On a re-roof, roof windows and loft ventilation go in before the tiles, and every new re-roof carries our 10 year guarantee. On a flat roof, rooflights and lanterns are fitted or resealed as the new covering goes on. We fit and repair roof windows from Welwyn Garden City and Hatfield across Hertfordshire, north and west London and Northamptonshire, and the photos on this page are our own roofs, roof windows included.
When you call, you speak to the familyBest Top Roofing is family-run. The family that answers the phone and gives you the quote is the family that turns up and does the job.
What is included
- New roof windows fitted in tiled and slate roofs
- Old roof windows taken out and replaced with a new window and flashing kit
- Leaks round the frame traced from the loft and from the roof
- Flashing kits renewed and tiles or slates re-cut and refitted round the frame
- Perished seals and failed flashings resealed
- Rafters trimmed and the opening framed for a new window
- Membrane lapped into the window collar so water runs past it
- Rooflights and roof lanterns on flat roofs fitted or resealed
Signs you need this
- A brown stain or drip on the ceiling below a roof window
- Water running down the inside of the frame after heavy rain
- Flashing round the window lifted, bent or pulling away
- Tiles round the window cracked, slipped or cut short
- An old roof window with perished seals that lets in draughts
Skylights and roof windows: our recent work
Every photo is one of our own jobs. Tap to enlarge.
Red interlocking tile roof with a new roof window and dry ridge, seen from the scaffold
Roofers battening a re-roof around a new roof window over red membrane
How it works
Survey and fixed price
Thomas checks the roof and the room or loft below, then sets out the window, the flashing and the price in writing.
Roof opened
Tiles or slates stripped round the opening, rafters trimmed and the frame set out square.
Window and flashing fitted
The window fixed in, the flashing kit dressed and the membrane lapped into the collar.
Re-tiled and checked
Tiles or slates cut back in round the frame, the window checked from inside and the site cleared.
A roof window only stays dry if the roofing round it is right. The family that quotes your skylight is the family that fits it, and the price is fixed in writing before we start.
Skylights and roof windows: your questions answered
Can you fit a skylight where there was no window before?
Yes. We open the roof, frame the opening between the rafters, fit the window with its flashing kit and tile or slate back round it. Thomas checks the rafters and the room below at the survey so the window sits where you want it.
Can you replace an old roof window?
Yes. The old window and its flashings come out, the opening is checked for rot, and the new window goes in with a new flashing kit. Tiles or slates round it are refitted so the roof looks as it did, with a sound window in it.
Why is my skylight leaking?
Most skylight leaks come from round the frame, not through the glass: a lifted or badly fitted flashing kit, tiles cut short at the sides, a blocked gutter at the head of the window or seals that have perished. We trace the water from the loft and the roof before pricing the repair.
Do I need planning permission for a roof window?
Most roof windows on a house come under permitted development, so they do not need planning permission as long as they sit close to the roof slope. Listed buildings, conservation areas and flats are different, and we tell you at the survey if yours needs a check first.
Can you fit a roof window during a re-roof?
Yes, and it saves money. The scaffold is up and the roof is open, so the window and its flashing go in before the tiles. Every new re-roof carries our 10 year workmanship guarantee in writing.
Do you fit rooflights on flat roofs?
Yes. Rooflights and roof lanterns are fitted or resealed as part of our EPDM, GRP and felt flat roofs, with the upstand built into the new covering. Our flat roofs page covers the full job.
Related services
Reviews
What customers say on Google
Dannie SmithQuoted the next day · June 2026
Thomas came and gave me a quote next day, very professional and clean work was carried out. I will be using best top roofing for all my projects going forward and would highly recommend them.
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R Vidya RLeaking felt roof repaired · September 2026
thanks to Thomas for fixing our roof. It was pleasure working with you. I feel confident that the water leak is accessed from all points and all problem addressed
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Lee SextonNew flat roof · April 2026
I needed a new flat roofing doing and this amazing company did it exactly how I wanted it. Highly recommended. Friendly and polite. Would use and again and tell all my friends and family.
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Mahmoud Al SuwwanRoof problem fixed · August 2026
We had a problem in our roof we called this company and they solved the problem so happy and satisfied. I really highly recommend if anyone needs roofing work done if I ever need a roofer again hopefully we don't if I ever did I will always use this company again, thank you so much, guys.
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Lisa DunneBlocked gutters cleared · April 2026
Cleaned out our gutters as were blocked and overflowing. Very happy with the job done. Thank you very much!
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Ligita KaledaiteChosen over other quotes · July 2026
Very friendly. Had couple of Quotes from other companys And this was the best company for it.
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Sally MaskellRoofing work by Thomas · June 2026
Very impressed with the work that Thomas has done. Definitely recommend.
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Scarlet BullRoofing work · August 2026
Professional, good quality work! Recommended.
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Checkatrade customerBalcony roof installation · August 2026
Fantastic, professional and polite throughout the job.
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Samuel PatersonRoofing work · October 2026
really nice guy, great work ethic
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ashley clarkeSpeedy quote · October 2026
Speedy quote and top quality work. Highly recommend really vlean and tidy job.
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Thushan ThushanRoof leak fixed · October 2026
Tomax did a great job. He came out promptly and fixed the roof leak straight away. Very happy with his service. Highly recommended!
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Claire McCarthyLeaking roof fixed · September 2026
Great experience, fixed our roof which was leaking, arrived on time and very friendly. Very happy overall!!
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Checkatrade customerPitched roof repair · September 2026
Great experience, fixed our roof which was leaking, arrived on time and very friendly. Very happy overall.
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10 year
re-roof
guarantee
Our guarantee
re-roof
guarantee
Every new re-roof guaranteed for 10 years, in writing
When we replace your roof, our workmanship is guaranteed for 10 years from the day we finish, and the membrane, tiles and slates carry their manufacturers' guarantees on top. Repairs and flat roofs are guaranteed too, with the terms for your job written on your quote. We are fully insured.
Covered
- Our workmanship on every new re-roof for 10 years
- Lead, flashings, ridges and verges we fit
- Flat roofs laid to the system's specification
- Repairs, with the terms written on the quote
On top
- Tile and slate manufacturer guarantees
- Membrane and flat roof system guarantees
- Photos of the finished job
- The same family to call if anything is wrong
Not covered
- Storm or accidental damage after completion
- Work altered or added by someone else
- Parts of the roof we did not work on
- Gutters left to block and overflow
The guarantee for your job is written on your quote before you agree to anything. Read the full guarantee.
Talk to us about skylights and roof windows
Ring or send the form. We come out, look at the roof, show you what is needed and give you a fixed written price. No pressure and no hidden extras.