- Guide price
- £2,750–£4,800
- Survey
- Free for new and replacement roofs
- Quote
- Fixed, in writing
- Coverage
- England, Wales, Scotland, NI
Derbyshire at a glance
- Largest towns
- Derby, Chesterfield, Long Eaton, Ilkeston
- Postcode areas
- DE, NG, S, SK
- Building control
- Derby City Council, Chesterfield Borough Council, Erewash Borough Council and 4 other councils
- Neighbouring areas
- Nottinghamshire · Staffordshire · South Yorkshire · Leicestershire
- Guide price region
- East Midlands (−2% on West Midlands rates)
How much does a new extension roof cost in Derbyshire?
Guide prices including VAT at East Midlands rates. 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), GRP, new deck + insulation | £2,950–£5,300 |
| Extension (20 m²), EPDM, insulation + 1 rooflight upstand | £2,950–£5,150 |
| Single garage (18 m²), EPDM rubber | £1,550–£2,750 |
Which flat roofs are common in Derbyshire?
Flat roofs in Derbyshire sit on lock-up garage blocks on estates, low-rise post-war blocks of flats and 1960s and 1970s link-detached houses with flat-roofed garages and porches. 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. Approximate 1991–2020 regional averages based on Met Office data.
Building regulations in England
Replacing more than half of a roof over a heated room usually counts as renovating a thermal element, so it is insulated to current standards and notified to building control. Renovated roofs over heated rooms are insulated to around 0.16 W/m²K where that's feasible, and new extension roofs are built to 0.15 W/m²K. In Derbyshire the application goes to Derby City Council, Chesterfield Borough Council, Erewash Borough Council and 4 other councils. More on the rules.
Which flat roof system suits a kitchen extension?
On a plain rectangular extension, EPDM rubber is a strong, quiet choice that can often be laid in one sheet. It handles the slight movement between an extension and the house well.
Where the roof has a lantern, several rooflights or an internal corner, GRP fibreglass forms neat, rigid details around each one. Torch-on felt is a proven layered system and keeps costs down, though near timber cladding or at fragile junctions we may prefer a cold-applied method. If the extension is overlooked from upstairs windows, a sedum green roof is worth considering, provided the structure can take the extra load.
Whatever the membrane, the insulation sits above the deck as a warm roof. Our warm vs cold roof guide explains why.
Why does water pond or leak where the extension meets the house?
Usually because the fall runs the wrong way, the abutment detail has failed, or the roof has sagged close to the wall. The junction with the house is the most common leak point on an extension roof.
If the roof falls towards the house, or the deck dips near the wall, water sits against the upstand and finds any weakness in the flashing above. Older roofs often have the felt simply turned up the brickwork with no cover flashing, or a flashing that has pulled out of its joint. A patch will not change a fall. We re-firr or use tapered insulation so water runs away from the wall, then form a new upstand, usually 150 mm above the finished roof, with a flashing chased into the mortar joint.
Rooflights and lanterns are the other weak point. A lantern needs a properly built kerb with the membrane dressed up and under its frame. We rebuild rooflight upstands within the roof job; we do not supply the lantern itself. Our guide to ponding water explains the causes in more depth.
Which towns in Derbyshire do we cover?
- Derby
- Chesterfield
- Long Eaton
- Ilkeston
- Swadlincote
- Staveley
- Belper
- Heanor
- Alfreton
- Dronfield
- Ripley
- Buxton
- New Mills
- Glossop
- Sinfin
Extension and kitchen roofs in Derbyshire: questions
Which towns in Derbyshire do you cover?
All of Derbyshire. The main towns have their own pages below, and if yours isn't listed we still cover it: send your postcode and we'll confirm.
How much does a new extension roof cost in Derbyshire?
£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.
Which postcode areas do you cover in Derbyshire?
All of Derbyshire, including the DE, NG, S, SK postcode areas. Send your full postcode and we'll confirm.
How do I know my extension roof needs replacing rather than repairing?
Repeated leaks, a soft deck, wet insulation or widespread cracking point to replacement. A single defect on a dry, sound roof can usually be repaired.
Can a sedum roof go on my extension?
Possibly, if the structure can carry the extra weight and the roof has suitable falls and drainage. We check the joists at survey before recommending it.
Can you keep my existing roof lantern?
Often, if the lantern itself is sound. We lift it, rebuild the kerb, dress the new membrane up the upstand and refit the lantern.
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