What do flat rooflights involve?
Across Hertfordshire, our flat rooflights work covers fixed double or triple glazed rooflights for flat roofs and extensions. Survey first, fixed price second, fitting third.
Across the South East, single-storey kitchen extensions on 1930s semis and post-war detached houses are where most flat rooflights and lanterns go. Many South East homes have been extended more than once, and an old dome over an earlier extension is often due for replacement.
Towns in Hertfordshire
Options we can specify
- Double or triple glazing
- Rain sensor if paired with an opening unit
- Plastered or lined internal reveal
- Square, rectangular or long-format sizes
- Solar-control or self-cleaning outer pane
- Pairs with an opening unit where you also need ventilation
- Slim sightlines from inside — mostly glass, little frame
Planning and building rules in England
In England a rooflight on a house is usually permitted development under Class C if it projects no more than 150 mm beyond the roof slope and sits no higher than the ridge. 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.
For English homes the energy rules ask for rooflights of 2.2 W/m²K or better and roof windows of 1.4 W/m²K (or WER Band B); most modern double glazed units meet both. 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.
Flat rooflights prices in Hertfordshire
Prices below are shown including and excluding VAT. In Hertfordshire, 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 |
How the job runs
- Tell us about the roof. Send the postcode, rough sizes and a photo or two through the form, WhatsApp or the guide-price tool.
- Free survey. For new installations a surveyor measures the opening, checks the roof build-up and talks through glass and options.
- Fixed written quote. You get the product, the work and the price in writing. Nothing is ordered or paid for until you agree.
- Fitting and handover. We fit, seal and make good, then hand over product data, warranties and any certificate paperwork.
Flat rooflights in nearby areas
Common questions
How long does it take?
Fitting into a prepared upstand usually takes a day. Forming a new opening in an existing roof, including making good inside, is often two to three days.
Can a flat rooflight be walked on?
Not unless it is designed as a walk-on unit with structural laminated glass. A standard flat rooflight is for light only — if the roof is used as a terrace, choose a walk-on rooflight instead.
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.
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.
Do you fit flat rooflights across Hertfordshire?
Yes. We survey and fit flat rooflights across Hertfordshire, including Watford, Hemel Hempstead, Stevenage.
