- Guide price
- £1,350–£2,600
- Survey
- Free for new and replacement roofs
- Quote
- Fixed, in writing
- Coverage
- England, Wales, Scotland, NI
Northamptonshire at a glance
- Largest towns
- Northampton, Corby, Kettering, Wellingborough
- Postcode areas
- NN
- Building control
- West Northamptonshire Council and North Northamptonshire Council
- Neighbouring areas
- Leicestershire · Bedfordshire · Warwickshire · Cambridgeshire
- Guide price region
- East Midlands (−2% on West Midlands rates)
How much does a new dormer roof cost in Northamptonshire?
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 |
|---|---|
| Dormer (8 m²), GRP, scaffold | £1,350–£2,600 |
| Single garage (18 m²), EPDM rubber | £1,550–£2,750 |
| Extension (20 m²), GRP, new deck + insulation | £2,950–£5,300 |
Which flat roofs are common in Northamptonshire?
Flat roofs in Northamptonshire sit on lock-up garage blocks on estates, low-rise post-war blocks of flats and 1930s semis with flat-roofed garages and kitchen extensions. 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 Northamptonshire the application goes to West Northamptonshire Council and North Northamptonshire Council. More on the rules.
Do I need building regulations approval for a dormer roof?
Usually, yes, if you are replacing most of the roof. A dormer roof sits over a heated room, so it counts as a thermal element, and renovating more than half of it normally means upgrading the insulation where feasible.
In England the renovation target is 0.16 W/m²K for homes, approved through building control or a competent person scheme. Wales usually needs approval for most re-roofing work. Scotland works through the council's building standards and, where required, a building warrant. Northern Ireland asks you to contact district council building control before starting.
Insulating above the deck raises the roof slightly. On a dormer, that extra height has to fit under the main roof tiles at the back edge, so the build-up is planned at survey. Re-covering a dormer that looks the same afterwards does not usually need planning permission, but a listed building or conservation area may bring extra controls. More on our building regulations page.
Is GRP or EPDM better on a dormer roof?
GRP fibreglass is often the first choice on a dormer, because it is laid as a liquid resin over a mat and forms neat, rigid edges, corners and drip details on a small roof. It cures to a hard surface that copes with occasional foot traffic during window cleaning or maintenance.
EPDM rubber works well on a plain rectangular dormer and can usually be laid as one sheet, with no field joins. Unlike GRP, it does not depend on resin curing conditions on the day. Torch-on felt can be used, but working a torch close to timber cladding, fascias and tiles needs extra care, so a cold-applied system is often chosen instead.
We recommend the system after surveying the dormer, its edges and how it meets the main roof.
Which towns in Northamptonshire do we cover?
Dormer roofs in Northamptonshire: questions
Which towns in Northamptonshire do you cover?
All of Northamptonshire. 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 dormer roof cost in Northamptonshire?
£1,350–£2,600 for an 8 m² GRP dormer roof including scaffold, 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 Northamptonshire?
All of Northamptonshire, including the NN postcode areas. Send your full postcode and we'll confirm.
Is a dormer roof cheaper than a garage roof?
Not by as much as the size suggests. Scaffold and the extra detailing at height mean a small dormer roof often costs about the same as a single garage roof.
How long does a GRP dormer roof last?
As an indicative range, GRP lasts 20–40 years with good specification and maintenance.
Does the room below need emptying?
No, but moving furniture away from the window and covering the floor is sensible. The room stays usable throughout.
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