- Guide price
- £3,100–£5,400
- Survey
- Free for new and replacement roofs
- Quote
- Fixed, in writing
- Coverage
- England, Wales, Scotland, NI
Cornwall at a glance
How much does a rooflight upstand cost in Cornwall?
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 Cornwall?
Flat roofs in Cornwall sit on lock-up garage blocks on estates, 1960s and 1970s link-detached houses with flat-roofed garages and porches and newer estates where the first extension roofs are now being replaced. 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 Cornwall the application goes to Cornwall 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.
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 Cornwall do we cover?
Rooflights in flat roofs in Cornwall: questions
Which towns in Cornwall do you cover?
All of Cornwall. 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 Cornwall?
£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 Cornwall?
It depends on where the roof is: in Cornwall that's Cornwall 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.
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 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 Cornwall →