Corby at a glance
- Postcode districts
- NN17, NN18
- Population
- about 68,164 (GeoNames)
- Council area
- North Northamptonshire Council
- Building approval
- North Northamptonshire Council building control, or a registered building control approver
- Nearest main town
- Northampton, about 19 miles
- Guide price region
- East Midlands (−2% on West Midlands rates)
Why choose a green roof in Corby?
If you're replacing an old flat roof in Corby, 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 and around Corby, flat roofs are typically found on bungalows with flat-roofed side extensions and dormers, and on lock-up garage blocks on estates. 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 Corby?
At East Midlands guide rates, a 20 m² insulated extension roof finished as a sedum green roof comes to £4,300–£7,900 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 | £4,300–£7,900 |
| Extension (20 m²), EPDM, new deck + insulation | £2,750–£4,800 |
How is a green roof built on top of a flat roof?
From the bottom up, a green roof is a deck, a waterproofing system with root protection, then drainage, filter, growing medium and plants. The waterproofing does the job of keeping water out. The green layers sit above it.
- Warm roof build-up: vapour control layer, insulation and waterproof membrane on the deck, then the green layers on top. This is the usual choice on a home extension being re-roofed.
- Inverted build-up: waterproofing on the deck, then insulation boards designed to sit above it, then the green layers. This is common on terraces and some commercial roofs.
- Root barrier: roots will exploit any weakness, so the membrane needs to be root-resistant. Some membranes are tested as root-resistant; others need a separate root barrier laid on top.
- Drainage and edges: a drainage layer carries surplus water to outlets, and a gravel or pebble strip is usually left around edges, outlets, upstands and rooflights to keep them clear and accessible.
Upstands still need to rise around 150 mm above the finished surface, which on a green roof means above the top of the growing medium. We check that at the survey, alongside the external fire performance of the build-up where the roof is close to a boundary.
What's included?
- Warm or inverted build-up to suit the roof
- Structural check of joists, deck and supports
- Drainage layer, filter and lightweight growing medium
- Pre-grown sedum blankets laid and watered in
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?
- Kettering · 7 mi
- Market Harborough · 10 mi
- Wellingborough · 13 mi
- Stamford · 14 mi
- Rushden · 15 mi
- Wigston · 18 mi
Green and sedum roofs in Corby: questions
Do you cover Corby?
Yes. Corby is part of our Northamptonshire coverage, including postcode districts NN17, NN18. 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 Corby?
Where the work needs approval it goes to North 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 Corby?
£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 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.
Does a green roof leak more than a normal flat roof?
No, as long as it is built correctly. The waterproofing beneath is what keeps water out, and the green layers protect it from sun and weather. The main risk is building it on a weak or ageing membrane.