- Guide price
- £3,100–£5,400
- Survey
- Free for new and replacement roofs
- Quote
- Fixed, in writing
- Coverage
- England, Wales, Scotland, NI
Dorset at a glance
How much does a rooflight upstand cost in Dorset?
Guide prices including VAT at South West rates. The fixed price comes after a free survey for new and replacement roofs.
| Job | Guide price inc VAT |
|---|---|
| Extension (20 m²), EPDM, insulation + 1 rooflight upstand | £3,100–£5,400 |
| Extension (20 m²), EPDM, new deck + insulation | £2,900–£5,050 |
| Extension (20 m²), EPDM with sedum green roof | £4,550–£8,350 |
Which flat roofs are common in Dorset?
Flat roofs in Dorset sit on 1960s and 1970s link-detached houses with flat-roofed garages and porches, lock-up garage blocks on estates and low-rise post-war blocks of flats. The South West averages roughly 1,260 mm of rain a year and many roofs face wind off the Atlantic, so we specify fixings and edge details for wind uplift as well as drainage. 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 Dorset the application goes to BCP Council and Dorset Council. More on the rules.
Should I choose a fixed or an opening rooflight, or a lantern?
Choose a fixed rooflight if you only want daylight, an opening one if the room needs ventilation, and a lantern if you want a raised, pitched glazed feature over a larger space.
- Fixed flat rooflights are the simplest and usually the cheapest option. They have the fewest moving seals, and the upstand detail is straightforward.
- Opening rooflights can be manual or electric, and electric units often include a rain sensor that closes them automatically. They need a power supply planned in before the ceiling is finished. Some are designed as hatches to give access to the roof.
- Roof lanterns have a framed, pitched glazed top that brings in more light and adds height to the room. They are heavier and larger, so the upstand has to be strong, level and square, and the joists around the opening may need strengthening.
Whatever you choose, it helps to settle on the unit before the roof is built, so the upstand can be made to the maker's sizes. If you've already chosen one, we build the upstand to suit it.
How long does a rooflight upstand last?
A properly built, insulated upstand with waterproofing dressed to the maker's details should last as long as the roof covering around it. The rooflight's own seals and opening parts may need attention sooner.
Upstands fail early when they are too low, poorly insulated or built on a deck that moves. Keeping the area around the rooflight clear of leaves and debris, checking the corners after storms from a safe position and cleaning the glazing gently all help. Never lean on or stand on a rooflight: most are fragile, and the roof around them should be treated as fragile too. The maintenance guide covers routine checks.
Which towns in Dorset do we cover?
Rooflights in flat roofs in Dorset: questions
Which towns in Dorset do you cover?
All of Dorset. 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 Dorset?
£3,100–£5,400 for a 20 m² insulated EPDM extension roof with one rooflight upstand, at South West 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 Dorset?
It depends on where the roof is: in Dorset that's BCP Council and Dorset 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.
Can a lantern go on a warm roof?
Yes. The upstand is built and insulated to the full height of the warm roof build-up, so the lantern sits at the right level above the finished surface.
Can I walk on a flat rooflight?
No, unless it is a unit specifically designed and rated for foot traffic. Treat standard rooflights and the roof around them as fragile.
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.
Everything about rooflights in flat roofs → · All flat roofing in Dorset →