Northampton at a glance
- Postcode districts
- NN1, NN2, NN3, NN4, NN7
- Population
- about 245,899 (GeoNames)
- Council area
- West Northamptonshire Council
- Building approval
- West Northamptonshire Council building control, or a registered building control approver
- Nearest main town
- Milton Keynes, about 15 miles
- Guide price region
- East Midlands (−2% on West Midlands rates)
Why choose a green roof in Northampton?
In a place like Northampton, many people look out over a flat extension or garage roof from upstairs. Grey felt or rubber isn't much of a view, and a sedum roof turns it into something green that changes colour through the seasons and flowers in summer.
Northampton's flat roofs are mostly on lock-up garage blocks on estates, with plenty on 1960s and 1970s link-detached houses with flat-roofed garages and porches too. The East Midlands is drier than the west of Britain, so most flat roofs here fail through age, UV and poor detailing at upstands rather than sheer rainfall.
How much does a green roof cost in Northampton?
For Northampton we use East Midlands rates: £4,300–£7,900 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 | £4,300–£7,900 |
| Extension (20 m²), EPDM, new deck + insulation | £2,750–£4,800 |
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
- Gravel strips kept clear around edges and outlets
- Root-resistant membrane or separate root barrier
- Drainage layer, filter and lightweight growing medium
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?
- Wellingborough · 9 mi
- Daventry · 12 mi
- Rushden · 12 mi
- Kettering · 12 mi
- Newport Pagnell · 13 mi
- Milton Keynes · 15 mi
Green and sedum roofs in Northampton: questions
Do you cover Northampton?
Yes. Northampton is part of our Northamptonshire coverage, including postcode districts NN1, NN2, NN3, NN4, NN7. 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 Northampton?
Where the work needs approval it goes to West Northamptonshire 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 Northampton?
£4,300–£7,900 for a 20 m² insulated extension roof finished as a sedum green roof, at East Midlands guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
Can a green roof have a rooflight in it?
Yes. The rooflight sits on a raised upstand with a gravel strip around it, so the planting stays clear of the glazing and the upstand stays visible and dry.
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.