Flat rooflights for Chiswick: the essentials
For Chiswick homes and buildings we offer flat rooflights: fixed double or triple glazed rooflights for flat roofs and extensions. We measure first, specify to the opening and confirm any planning or building-control points before quoting.
Mansard and loft conversions are common across London, and roof windows are often set out alongside dormers on the rear slope. Flat rooflights suit landings, bathrooms and rear extensions with flat roofs.
Jobs in Chiswick are planned around access: whether the roof can be reached from the garden, whether a hoist or crane is needed, and where we can park. We check this when we measure.
Choices for your Chiswick project
- Integral or fitted blinds
- Plastered or lined internal reveal
- Rain sensor if paired with an opening unit
- Frame colours: anthracite, black, white or RAL
- Insulated kerb or timber upstand built to suit
- Fixed units are simple, quiet and low-maintenance
- Even, top-down daylight across the whole room
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)
- The roof membrane must be dressed up the upstand before the unit goes on
Planning and building rules for Chiswick
English householder permitted development (Class C) normally covers rooflights that stand no more than 0.15 m proud of the roof plane and stay below the highest part of the roof. 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.
Building Regulations Approved Document L sets a limiting U-value of 2.2 W/m²K for new or replacement rooflights in existing homes, measured in the horizontal plane; roof windows need 1.4 W/m²K or a Band B energy rating. 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.
Our planning guide covers each nation in more detail.
What do flat rooflights cost in Chiswick?
Prices below are shown including and excluding VAT. In Chiswick, as elsewhere, making good inside and access equipment are the main variables.
| 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 |
From enquiry to finished job
- 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.
- Fit and make good. We fit, seal, test and finish the reveal, then hand over the paperwork.
Flat rooflights near Chiswick
Related work in Chiswick
Flat rooflights in Chiswick: questions
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.
How do I book a survey in Chiswick?
Send your postcode and, if you can, a photo of the roof and the room. We offer a survey date when we reply.
Can you work alongside my builder in Chiswick?
Yes. On new extensions we fit once the opening and upstand are ready and coordinate dates with your builder.
