- Guide price
- £1,350–£2,500
- Survey
- Free for new and replacement roofs
- Quote
- Fixed, in writing
- Coverage
- England, Wales, Scotland, NI
Lancashire at a glance
- Largest towns
- Preston, Burnley, Blackburn, Blackpool
- Postcode areas
- BB, FY, L, LA, OL, PR, WN
- Building control
- Preston City Council, Burnley Borough Council, Blackburn with Darwen Borough Council and 10 other councils
- Neighbouring areas
- Greater Manchester · Merseyside · Cheshire · West Yorkshire
- Guide price region
- North West (−5% on West Midlands rates)
How much does a new dormer roof cost in Lancashire?
Guide prices including VAT at North West 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–£2,500 |
| Single garage (18 m²), EPDM rubber | £1,500–£2,650 |
| Extension (20 m²), GRP, new deck + insulation | £2,850–£5,100 |
Which flat roofs are common in Lancashire?
Flat roofs in Lancashire sit on newer estates where the first extension roofs are now being replaced, 1930s semis with flat-roofed garages and kitchen extensions and shops with flat-roofed rear stores below flats. The North West is one of England's wetter regions, averaging roughly 1,290 mm of rain a year, so falls, outlets and well-detailed upstands matter more than the membrane colour. 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 Lancashire the application goes to Preston City Council, Burnley Borough Council, Blackburn with Darwen Borough Council and 10 other councils. 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.
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 Lancashire do we cover?
- Preston
- Burnley
- Blackburn
- Blackpool
- Morecambe
- Lancaster
- Lytham St Annes
- Skelmersdale
- Leyland
- Accrington
- Chorley
- Darwen
- Thornton-Cleveleys
- Nelson
- Fleetwood
- Ormskirk
- Rawtenstall
- Colne
- Poulton-le-Fylde
- Heysham
- Haslingden
Dormer roofs in Lancashire: questions
Which towns in Lancashire do you cover?
All of Lancashire. 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 Lancashire?
£1,350–£2,500 for an 8 m² GRP dormer roof including scaffold, at North West guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
Which postcode areas do you cover in Lancashire?
All of Lancashire, including the BB, FY, L, LA, OL, PR, WN postcode areas. Send your full postcode and we'll confirm.
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.
How long does a GRP dormer roof last?
As an indicative range, GRP lasts 20–40 years with good specification and maintenance.
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