Cowley at a glance
- Postcode districts
- OX4
- Population
- about 16,500 (GeoNames)
- Council area
- Oxford City Council
- Building approval
- Oxford City Council building control, or a registered building control approver
- Nearest main town
- Oxford, about 3 miles
- Guide price region
- South East (+10% on West Midlands rates)
Why choose a green roof in Cowley?
If you're replacing an old flat roof in Cowley, it's worth deciding whether to add sedum at the same time. If the structure can take it, that is the ideal moment, because the waterproofing is new and the green layers won't need lifting for a long time.
In a town like Cowley, flat roofs are commonly found on shops with flat-roofed rear stores below flats or bungalows with flat-roofed side extensions and dormers. Much of the South East sits in the drier Thames catchment at roughly 730 mm of rain a year, so the usual failures are at joints, upstands and outlets rather than from sheer volume of rain.
How much does a green roof cost in Cowley?
For Cowley we use South East rates: £4,850–£8,900 is the guide for a 20 m² insulated extension roof finished as a sedum green roof, VAT included. 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 | £4,850–£8,900 |
| Extension (20 m²), EPDM, new deck + insulation | £3,100–£5,350 |
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?
- Gravel strips kept clear around edges and outlets
- Root-resistant membrane or separate root barrier
- Structural check of joists, deck and supports
- 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 Cowley: questions
Do you cover Cowley?
Yes. Cowley is part of our Oxfordshire coverage, including postcode districts OX4. 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 Cowley?
Where the work needs approval it goes to Oxford City Council 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 Cowley?
£4,850–£8,900 for a 20 m² insulated extension roof finished as a sedum green roof, at South East 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.
Can you put a green roof on a pitched roof?
We install green roofs on flat roofs only. Sloping green roofs need extra restraint to stop the growing medium slipping, and they are a specialist job outside our work.