How we approach flat rooflights in Harpenden
For Harpenden 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.
Across the South East, single-storey kitchen extensions on 1930s semis and post-war detached houses are where most flat rooflights and lanterns go. Flat rooflights suit landings, bathrooms and rear extensions with flat roofs.
Neighbouring towns include St Albans (8 km) and Luton (8 km). We offer a survey date when we reply to your enquiry.
Choices for your Harpenden project
- Insulated kerb or timber upstand built to suit
- Frame colours: anthracite, black, white or RAL
- Square, rectangular or long-format sizes
- Plastered or lined internal reveal
- Rain sensor if paired with an opening unit
- Pairs with an opening unit where you also need ventilation
- Slim sightlines from inside — mostly glass, little frame
Things we check at survey
- Needs a properly formed upstand — usually at least 150 mm above the finished roof surface (check the manufacturer's figure)
- New openings in an existing roof need a structural check on joists
Planning and building rules for Harpenden
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.
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. In an extension, glazing including rooflights is normally limited to 25% of the new floor area plus any windows or doors the extension covers, unless a whole-house calculation shows otherwise.
See our building regulations guide for U-values, glazing limits and self-certification.
Flat rooflights prices in Harpenden
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 |
What happens next
- Tell us what you have. Send the AL5 postcode, a rough size and a couple of photos.
- Free site visit. For new installs we survey free, measure and confirm the roof detail.
- Written price. You receive a fixed price listing the unit, the work and the lead time.
- Fitting and handover. We install, clean down and leave product and warranty documents.
Nearby towns
Related work in Harpenden
Common 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.
Do I need to be at home for the survey in Harpenden?
Yes — someone needs to let us into the room below and, where possible, show us how the roof is reached.
Do you fit flat rooflights in Harpenden?
Yes. We survey and fit flat rooflights in Harpenden and across Hertfordshire. Send your postcode and we will offer a survey date when we reply.
