- Guide price
- £1,450–£2,800
- Survey
- Free for new and replacement roofs
- Quote
- Fixed, in writing
- Coverage
- England, Wales, Scotland, NI
Cambridgeshire at a glance
- Largest towns
- Peterborough, Cambridge, Wisbech, St Neots
- Postcode areas
- CB, PE
- Building control
- Peterborough City Council, Cambridge City Council, Fenland District Council and 2 other councils
- Neighbouring areas
- Northamptonshire · Bedfordshire · Hertfordshire · Suffolk
- Guide price region
- East of England (+5% on West Midlands rates)
How much does a new dormer roof cost in Cambridgeshire?
Guide prices including VAT at East of England rates. The fixed price comes after a free survey for new and replacement roofs.
| Job | Guide price inc VAT |
|---|---|
| Dormer (8 m²), GRP, scaffold | £1,450–£2,800 |
| Single garage (18 m²), EPDM rubber | £1,700–£2,950 |
| Extension (20 m²), GRP, new deck + insulation | £3,150–£5,650 |
Which flat roofs are common in Cambridgeshire?
Flat roofs in Cambridgeshire sit on shops with flat-roofed rear stores below flats, 1930s semis with flat-roofed garages and kitchen extensions and newer estates where the first extension roofs are now being replaced. The East of England is the driest part of Britain, with parts of the Anglian region around 630 mm a year, so summer heat and UV, not rainfall, do most of the ageing on a felt roof. 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 Cambridgeshire the application goes to Peterborough City Council, Cambridge City Council, Fenland District Council and 2 other councils. More on the rules.
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.
How long does a dormer roof replacement take?
The roofing itself typically takes one to three days, with scaffold going up before and coming down after. Allow a few extra days overall for the scaffold.
The room under the dormer stays usable, though it will be noisy during the strip-out, and dust can fall through gaps around the ceiling. Moving furniture away from the window helps. Scaffold usually needs space on the drive or garden, and sometimes a pavement licence. GRP has a strong smell while it cures, so keep the dormer windows shut on the day it is laid.
Which towns in Cambridgeshire do we cover?
Dormer roofs in Cambridgeshire: questions
Which towns in Cambridgeshire do you cover?
All of Cambridgeshire. 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 Cambridgeshire?
£1,450–£2,800 for an 8 m² GRP dormer roof including scaffold, at East of England guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
Which council handles building control for a flat roof in Cambridgeshire?
It depends on where the roof is: in Cambridgeshire that's Peterborough City Council, Cambridge City Council, Fenland District Council and 2 other councils. 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. We confirm which applies at the survey.
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.
Why does my dormer leak at the back where it meets the roof?
That junction is the most common leak point, usually because the upstand or flashing under the tiles has failed. A proper re-roof rebuilds it.
Can you replace the lead on my dormer at the same time?
Yes, where lead forms part of the dormer abutment or cheek flashings, we include renewing it in the roof job.
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