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 upgrade to a warm roof in Corby?
Converting a garage, loft space or outbuilding to a room in Corby changes what the roof needs to do. Once the space is heated, the roof is expected to perform to a higher standard, and a warm build-up is usually the simplest way to get there.
Corby's flat roofs are mostly on low-rise post-war blocks of flats, with plenty on newer estates where the first extension roofs are now being replaced 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 warm roof upgrade cost in Corby?
For Corby we use East Midlands rates: £2,750–£4,800 is the guide for a 20 m² extension roof in EPDM with a new deck and insulation, VAT included. The fixed price comes after a free survey for new and replacement roofs.
| Job | Guide price inc VAT |
|---|---|
| Extension (20 m²), EPDM, new deck + insulation | £2,750–£4,800 |
| Extension (20 m²), EPDM with sedum green roof | £4,300–£7,900 |
How long does a warm roof last?
The insulation in a warm roof should last for the life of the waterproofing above it, as long as it stays dry. Rigid PIR boards don't settle or slump in the way some loose insulation can.
The waterproofing is what sets the timescale. EPDM is typically quoted at 25 to 50 years, GRP at 20 to 40 years and modern torch-on felt at 15 to 25 years with good specification and care. A warm build-up also helps the deck, because keeping it warm and dry lowers the risk of condensation rot. If the waterproofing fails and water gets into the insulation, the wet boards should be replaced, so leaks need prompt attention. The lifespan guide compares the systems.
What's included?
- Rigid insulation boards sized to the U-value target
- Survey of the deck, joists and existing insulation
- Upstands, trims and kerbs reset to the new roof level
- Vapour control layer on the warm side of the insulation
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
Warm roof insulation upgrades 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 warm roof upgrade cost in Corby?
£2,750–£4,800 for a 20 m² extension roof in EPDM with a new deck and insulation, at East Midlands guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
How thick does flat roof insulation need to be?
It depends on the insulation product and the U-value target. With common PIR boards, meeting a renovation target usually means well over 100 mm. Thinner, higher-performance boards are available where height is tight.
Can you insulate a flat roof from inside instead?
It is possible, but insulating between or under the joists creates a cold roof, which needs ventilation and carries a higher condensation risk. When the roof is being re-covered anyway, a warm roof from above is usually the better option.