Southwark at a glance
- Postcode districts
- SE5, SE15, SE17, SE22, SE14, SE11, SE1, SE8
- Council area
- London Borough of Southwark
- Building approval
- London Borough of Southwark building control, or a registered building control approver
- Guide price region
- London (+20% on West Midlands rates)
What does a dormer roof in Southwark need?
In Southwark, as anywhere, it often makes sense to replace a dormer roof while scaffold is already up for other work, such as new windows, rendering or repairs to the main roof. Sharing the scaffold keeps costs down and means every edge of the dormer can be checked at the same time.
In and around Southwark, flat roofs are typically found on Victorian and Edwardian terraces with flat-roofed back additions, and on mansion blocks and purpose-built flats with large flat roofs. The Thames basin is one of the drier parts of Britain at roughly 730 mm of rain a year, but summer heat is the bigger test here: dark membranes on south-facing roofs swing a long way in temperature.
How much does a new dormer roof cost in Southwark?
At London guide rates, an 8 m² GRP dormer roof including scaffold comes to £1,700–£3,200 including VAT. The fixed price comes after a free survey for new and replacement roofs.
| Job | Guide price inc VAT |
|---|---|
| Dormer (8 m²), GRP, scaffold | £1,700–£3,200 |
| Single garage (18 m²), EPDM rubber | £1,900–£3,350 |
| Extension (20 m²), GRP, new deck + insulation | £3,600–£6,450 |
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.
What's included?
- Scaffold with edge protection, priced in the quote
- Strip-out of the old covering and deck repairs
- Free survey of the dormer roof, cheeks and main roof junction
- New membrane, drip trims and back-edge abutment under the tiles
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?
Dormer roofs in Southwark: questions
Do you cover Southwark?
Yes. Southwark is part of our London coverage, including postcode districts SE5, SE15, SE17, SE22, SE14, SE11 and 2 more. 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 Southwark?
Where the work needs approval it goes to London Borough of Southwark 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 new dormer roof cost in Southwark?
£1,700–£3,200 for an 8 m² GRP dormer roof including scaffold, at London guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
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.
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.