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Rooflights in flat roofs across Buckinghamshire

Across Buckinghamshire, as everywhere, most rooflight leaks start at a low or poorly finished upstand rather than at the glazing. When we fit a rooflight or lantern as part of a flat roof job, the opening, the kerb, the membrane and the joint with the frame are all done together and checked before we leave.

Rubber membrane being dressed up the timber upstand of a new flat rooflightComputer-generated example image
Guide price
£3,300–£5,750
Survey
Free for new and replacement roofs
Quote
Fixed, in writing
Coverage
England, Wales, Scotland, NI

Buckinghamshire at a glance

Largest towns
Milton Keynes, High Wycombe, Aylesbury, Bletchley
Postcode areas
HP, MK, SL
Building control
Milton Keynes City Council and Buckinghamshire Council
Neighbouring areas
Bedfordshire · Hertfordshire · Berkshire · Oxfordshire
Guide price region
South East (+10% on West Midlands rates)

How much does a rooflight upstand cost in Buckinghamshire?

Guide prices including VAT at South East rates. The fixed price comes after a free survey for new and replacement roofs.

JobGuide price inc VAT
Extension (20 m²), EPDM, insulation + 1 rooflight upstand£3,300–£5,750
Extension (20 m²), EPDM, new deck + insulation£3,100–£5,350
Extension (20 m²), EPDM with sedum green roof£4,850–£8,900

Which flat roofs are common in Buckinghamshire?

Flat roofs in Buckinghamshire sit on low-rise post-war blocks of flats, 1930s semis with flat-roofed garages and kitchen extensions and 1960s and 1970s link-detached houses with flat-roofed garages and porches. Much of the South East sits in the drier Thames catchment at roughly 730 mm of rain a year, so the usual failures are at joints, upstands and outlets rather than from sheer volume of rain. Approximate 1991–2020 regional averages based on Met Office data.

Building regulations in England

Replacing more than half of a roof over a heated room usually counts as renovating a thermal element, so it is insulated to current standards and notified to building control. Renovated roofs over heated rooms are insulated to around 0.16 W/m²K where that's feasible, and new extension roofs are built to 0.15 W/m²K. In Buckinghamshire the application goes to Milton Keynes City Council and Buckinghamshire Council. More on the rules.

Why is my flat rooflight leaking, and should it be repaired or replaced?

Most rooflight leaks come from the upstand detail rather than the glass: the membrane has split or pulled away at a corner, the upstand is too low, or the flashing at the top has failed. Repair the detail if the unit and the roof around it are sound.

Drips on the inside of the upstand in cold weather may be condensation rather than a leak, especially on older, uninsulated kerbs or single-glazed domes. Warm, moist air from a kitchen or bathroom meets the cold surface and condenses.

If the roof covering is near the end of its life, it is usually better to rebuild the upstand properly as part of a replacement, ideally with a new insulated kerb, rather than patching the old detail. Our repair or replace guide and flat roof repairs page cover the options.

Do rooflights in flat roofs need building regulations approval?

Usually, yes, for a new opening, because cutting through the roof and trimming joists is a structural alteration. Approval may also be needed because the roof itself is being re-covered.

New rooflights need to meet the energy efficiency standards for glazing, so that the unit doesn't become a weak point in an insulated roof. Many rooflights have a laminated inner pane, so that if the glass breaks it stays in place rather than falling into the room, which is worth asking for over kitchens, living spaces and stairs. Close to a boundary, the fire performance of the roof, including any rooflights, can matter under the fire safety rules.

Whether you need planning permission depends on the property and the unit. A raised lantern changes the roofline more than a flat rooflight, and listed buildings and conservation areas have stricter rules, which also differ between the four nations. We handle building control or building standards where it is needed. The building regulations page and the planning guide explain more.

Which towns in Buckinghamshire do we cover?

Rooflights in flat roofs in Buckinghamshire: questions

Which towns in Buckinghamshire do you cover?

All of Buckinghamshire. The main towns have their own pages below, and if yours isn't listed we still cover it: send your postcode and we'll confirm.

How much does a rooflight upstand cost in Buckinghamshire?

£3,300–£5,750 for a 20 m² insulated EPDM extension roof with one rooflight upstand, at South East guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.

Which council handles building control for a flat roof in Buckinghamshire?

It depends on where the roof is: in Buckinghamshire that's Milton Keynes City Council and Buckinghamshire Council. Replacing more than half of a roof over a heated room usually counts as renovating a thermal element, so it is insulated to current standards and notified to building control. We confirm which applies at the survey.

Why does my rooflight drip in winter?

If it only drips in cold weather and not when it rains, it is probably condensation on a cold, poorly insulated upstand or older glazing. Better ventilation helps, and an insulated kerb and modern unit usually fix it.

Will an opening rooflight let rain in if I leave it open?

Many electric opening rooflights include a rain sensor that closes them automatically when it starts raining. With manual units, it's up to you to close them.

Can a rooflight be added to an existing flat roof?

Yes, if the structure allows it. The opening is cut, the joists are trimmed and an upstand is built and waterproofed into the existing covering. On an older roof, it is often better to do it as part of a replacement.

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