A flat roof replacement strips the old covering from a low-pitched roof and lays a new waterproof system, usually EPDM rubber, GRP fibreglass or torch-on felt, over a sound deck with correct falls, upstands, trims and outlets so rainwater drains away.
If you live in Westminster and are weighing up a new flat roof, the starting point is a visit to measure up and talk through what you want, which costs nothing. We cover homes across SW1, SW1A, SW1E and SW1H, and a typical project of this kind in London lands somewhere in the £2,600–£5,800 bracket, including VAT. The exact figure depends on size, access and the finish you choose.
- Guide price
- £2,600–£5,800 inc VAT
- Time on site
- 1–3 days for most roofs
- Postcodes
- SW1, SW1A, SW1E, SW1H and SW1P
- Planning rules
- England
- Local area
- London
- Survey
- Free, with a written quote
What should you budget for a new flat roof in Westminster?
Below is a breakdown of typical costs for a new flat roof in Westminster. Because rates in London are about 30% above the national guide, the overall guide comes to £2,600–£5,800, including VAT. Size, materials and access move the figure, and a free-of-charge survey settles it.
| Type of job | What it usually involves | Guide in Westminster |
|---|---|---|
| Small roof (up to 8m²) | A dormer, bay, porch or small garage roof re-covered in EPDM or GRP. | £1,050–£2,600 |
| Extension or garage (15–25m²) | A typical extension or single garage roof stripped and re-covered. | £2,600–£5,800 |
| Large or new warm roof | Larger roofs, or roofs needing a new deck and insulation build-up. | £5,200–£11,500 |
Your price depends mostly on:
- Covering system: EPDM, GRP or torch-on felt
- Condition of the deck and joists underneath
- Insulation upgrades and changes to roof height at edges
- Number of rooflights, pipes and upstands to detail
What does the job include in Westminster?
- Stripping and disposal of the old roof covering
- Replacement of rotten or soft deck boards
- Insulation upgrade to a warm roof build-up where agreed
- New EPDM, GRP or torch-on felt membrane laid to falls
- New trims, outlets and gutter connections
- Rooflights refitted or replaced where required
Homes in London
London's housing is dominated by Victorian and Edwardian terraces, often in yellow London stock brick, with Georgian terraces in central districts and mansion blocks across many inner areas. Outer boroughs have large belts of interwar semis, and there are extensive post-war council estates. Many houses have been split into flats, and conservation areas are widespread.
London Clay shrinks and swells with the seasons, and street trees close to houses can contribute to movement, which affects foundation design.
Whatever era your Westminster home dates from, we plan a new flat roof around how it is actually built rather than a one-size-fits-all specification.
Do you need permission in Westminster?
For anyone in Westminster, the relevant framework is England's. The summary below is general, so we always contact the council about your address before putting a price in writing.
Re-roofing a house with similar materials does not usually need planning permission in England. Listed buildings and conservation areas may need consent if the covering changes.
Replacing more than a quarter of a roof’s covering counts as renovation under Building Regulations, so the work is notified and the roof insulation may need upgrading. Bats are protected across the UK; if they roost under roof tiles, soffits or fascias, work stops and a licensed ecologist advises before it restarts.
Rules change and every property is different, so we check the planning history and constraints for your address before we quote.
The four stages
We look at the job
We begin by looking at the job in person. During the free survey we discuss options, materials and budget for a new flat roof, and photograph or measure anything the quote needs to reflect.
Price and scope agreed
The quote arrives in writing, not over the phone. It covers the full scope, the finishes you've chosen, any exclusions and the payment schedule, with a fixed price tied to that specification.
Booking the work
Once you accept, we agree start dates, order materials and deal with any planning, building control or neighbour notices the job needs. You'll know who is coming and when before work begins.
Build and hand over
Our trades complete a new flat roof while your point of contact keeps you updated. When everything is finished, we clear the site, take away waste and go through the result with you before handover.
How we work
Questions about a new flat roof in Westminster
Should I insulate my flat roof when it is replaced?
Replacing a flat roof is the most cost-effective time to add insulation, because the covering is already off. A warm roof, with insulation laid above the deck, keeps the structure warm and reduces condensation risk. Building regulations may require insulation when a large part of the roof is renewed. It raises the roof height slightly, which affects trims and upstands.
Can I stay at home during the work?
In most cases, yes. Most people can live at home throughout, and we plan the work to keep disruption down by protecting floors, agreeing working hours and keeping access routes clear. Bigger jobs affecting kitchens, bathrooms or heating may mean a short spell with reduced facilities, and we talk this through with you at the survey.
Who do I deal with during the job?
One point of contact manages your project from survey to handover. They schedule the trades working under our contract, keep you updated on progress, and are the person to call with any question. You don't need to coordinate builders, electricians or decorators separately, because that is part of what we do.
Can you repair my flat roof instead of replacing it?
A flat roof can often be repaired if the damage is limited to a small split, a failed joint or a loose upstand and the rest of the covering is sound. If the deck is soft, the covering is blistered or cracked across the roof, or leaks keep returning, replacement is usually better value. We assess the whole roof and give you an honest recommendation.
How much does a new flat roof cost?
Re-covering a typical 15–25m² extension or garage roof costs £2,600–£5,800. As a guide, allow around £75–£170 per square metre plus fixed costs for stripping, waste and access, with torch-on felt at the lower end and GRP or EPDM with new decking or insulation at the top. Small dormer and porch roofs cost less overall but more per square metre. We confirm a fixed price after the survey.
Nearby towns
From SW1, SW1A, SW1E and SW1H to the edges of Westminster and on into Pimlico, Soho and Chelsea, we can arrange a site visit and a written quote for your project, planned around dates that work for you.