Flat rooflights for Dorchester: the essentials
Our flat rooflights service in Dorchester covers fixed double or triple glazed rooflights for flat roofs and extensions. Every job starts with a survey of the opening, the roof covering and the room below, and a fixed written price.
Holiday lets and second homes across the South West often want roof windows with blinds and remote opening for when the house is empty. Think of flat rooflights for kitchen extensions, side returns and flat-roofed back rooms.
Neighbouring towns include Weymouth (12 km) and Bridport (23 km). We offer a survey date when we reply to your enquiry.
What you can choose
- Plastered or lined internal reveal
- Integral or fitted blinds
- Solar-control or self-cleaning outer pane
- Insulated kerb or timber upstand built to suit
- Square, rectangular or long-format sizes
- Double or triple glazed with a warm-edge spacer
- Fixed units are simple, quiet and low-maintenance
Before you order: points to check
- Needs a properly formed upstand — usually at least 150 mm above the finished roof surface (check the manufacturer's figure)
- Rooflights count toward glazing in an extension, which matters for Building Regulations energy and overheating rules
Do you need permission in Dorchester?
Most rooflights on English houses do not need planning permission, provided they keep within 150 mm of the roof surface and below the ridge line. A rooflight on a side-facing slope must be obscure-glazed, and fixed shut unless the opening part is more than 1.7 m above the floor.
Under Approved Document L, a rooflight added to an English home must achieve at least 2.2 W/m²K (horizontal plane), and a roof window 1.4 W/m²K or Window Energy Rating Band B. The Future Homes and Buildings Standards, published in March 2026, apply from 24 March 2027 and keep the 2.2 W/m²K limit for rooflights.
Read the planning permission guide before you commit to a design.
What do flat rooflights cost in Dorchester?
The ranges below are typical for straightforward jobs; your fixed price follows a survey of your roof.
| Option | Guide price inc VAT | Ex VAT |
|---|---|---|
| Large or triple glazed (1500 × 2500 mm and up) | £2,395 – £4,195 | £1,995 – £3,495 |
| Mid-size double glazed (1000 × 2000 mm) Typical | £1,675 – £2,395 | £1,395 – £1,995 |
| Small double glazed (up to 1000 × 1000 mm) | £1,195 – £1,795 | £995 – £1,495 |
How the job runs
- Send the details. Postcode, rough size and a photo of the roof and room.
- Survey. We measure the opening, check the roof build-up and agree the options.
- Agree the quote. You approve the specification and price before anything is ordered.
- Installation day. Usually one day into a prepared opening, longer for new openings.
Flat rooflights near Dorchester
Related work in Dorchester
Questions about flat rooflights in Dorchester
Do flat rooflights leak?
A well-fitted flat rooflight should not leak. Leaks almost always come from the upstand or membrane detailing, not the glass unit, which is why the upstand height and the way the roof covering is dressed up and under the frame matter more than the brand.
Can you fit into my existing flat roof?
Yes. We form a new opening, trim the joists, build and waterproof an upstand and make good the ceiling. A survey confirms the joist direction and roof build-up first.
Double or triple glazing?
Double glazing suits most domestic jobs. Triple glazing improves thermal performance and cuts noise from rain, which is worth it over bedrooms or where the energy calculation is tight.
Do you fit flat rooflights in Dorchester?
Yes. We survey and fit flat rooflights in Dorchester and across Dorset. Send your postcode and we will offer a survey date when we reply.
Is the survey in Dorchester free?
Yes for new installations. Repair visits are charged, and we tell you the price before we book.
