Barnet at a glance
- Postcode districts
- N20, N11, N14, N12, EN4, N3, EN5, NW7 and 1 more
- Council area
- London Borough of Barnet
- Building approval
- London Borough of Barnet building control, or a registered building control approver
- Guide price region
- London (+20% on West Midlands rates)
Why choose a green roof in Barnet?
Garden rooms and outbuildings in Barnet, as elsewhere, often have small flat roofs that are seen from the house and garden. A sedum finish helps them blend in, provided the structure is strong enough and the roof underneath is built properly.
In a town like Barnet, flat roofs are commonly found on shops with flat-roofed stores below flats above or mansion blocks and purpose-built flats with large flat roofs. The Thames basin is one of the drier parts of Britain at roughly 730 mm of rain a year, but summer heat is the bigger test here: dark membranes on south-facing roofs swing a long way in temperature.
How much does a green roof cost in Barnet?
At London guide rates, a 20 m² insulated extension roof finished as a sedum green roof comes to £5,300–£9,700 including VAT. The fixed price comes after a free survey for new and replacement roofs.
| Job | Guide price inc VAT |
|---|---|
| Extension (20 m²), EPDM with sedum green roof | £5,300–£9,700 |
| Extension (20 m²), EPDM, new deck + insulation | £3,350–£5,850 |
Can a green roof go on my existing flat roof?
Only if the existing waterproofing is sound, root-resistant or protected by a root barrier, and has plenty of life left. In most cases it makes more sense to lay a green roof as part of a replacement.
Once the sedum, substrate and drainage layers are down, the membrane underneath is hard to inspect and expensive to repair, because the green layers have to be lifted to get to it. Putting a green roof on an ageing covering risks paying for the greenery twice. Our repair or replace guide helps you judge whether your current roof is a sensible base.
As for planning, re-covering a house roof normally needs no application if its appearance doesn't change materially. Because a green roof does change how a roof looks, check with your council, especially for listed buildings, conservation areas and roofs that are easily seen. The planning guide has more.
What's included?
- Pre-grown sedum blankets laid and watered in
- Drainage layer, filter and lightweight growing medium
- Gravel strips kept clear around edges and outlets
- Warm or inverted build-up to suit the roof
Building regulations in England
Replacing more than half of a flat roof over a heated room usually counts as renovating a thermal element, so the roof is insulated to around 0.16 W/m²K where that's technically and economically feasible, and the work is notified to building control: the council or a registered building control approver, unless a registered competent person self-certifies it. A roof on a new extension is built to 0.15 W/m²K. Patch repairs, and most unheated detached garages, don't trigger the upgrade. Structural changes, or a new covering that adds 15% or more to the roof's weight, also need approval. More on the rules.
Which nearby areas do we also cover?
Green and sedum roofs in Barnet: questions
Do you cover Barnet?
Yes. Barnet is part of our London coverage, including postcode districts N20, N11, N14, N12, EN4, N3 and 3 more. Surveys and roofs are carried out by vetted roofing teams working under S&K Property Investments and Improvement Ltd.
Who checks building regulations for a flat roof in Barnet?
Where the work needs approval it goes to London Borough of Barnet building control, or a registered building control approver. We tell you at the survey whether your job needs it and deal with the paperwork as part of the quote.
How much does a green roof cost in Barnet?
£5,300–£9,700 for a 20 m² insulated extension roof finished as a sedum green roof, at London guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
Can you put a sedum roof on a garage?
Often, yes, if the structure is strong enough. Many older garage roofs have light timbers, so a structural check comes first and strengthening may be needed.
What happens if a green roof needs repairing?
The green layers are lifted around the problem area, the membrane is repaired, and the layers are relaid. Building on a sound, long-life membrane in the first place keeps that to a minimum.