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.
We take on a new flat roof throughout Isleworth and the surrounding TW1, TW3, TW4 and TW5 postcodes, as well as in Hounslow, Heston and Richmond. The guide range for this work in London is £2,600–£5,800 including VAT; where your project falls depends on its size, the materials you pick and how easy the site is to reach. A free survey turns that range into a fixed figure.
- Guide price
- £2,600–£5,800 inc VAT
- Time on site
- 1–3 days for most roofs
- Postcodes
- TW1, TW3, TW4, TW5 and TW7
- Planning rules
- England
- Local area
- Greater London
- Survey
- Free, with a written quote
How much does a new flat roof cost in Isleworth?
What should you budget for a new flat roof in Isleworth? Use the figures below as a starting point. Prices in London sit about 30% above the national guide, so the range here is £2,600–£5,800 including VAT. Your fixed price comes in writing once we've surveyed the property, at no charge.
| Type of job | What it usually involves | Guide in Isleworth |
|---|---|---|
| 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:
- Roof area and access to the roof
- 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 Isleworth?
- Survey of the covering, deck, falls, upstands and drainage
- 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
- Upstands, flashings and drip edges finished neatly
- New trims, outlets and gutter connections
Building in Isleworth
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.
Terraces suit side-return extensions and rear dormer loft conversions; interwar semis commonly take hip-to-gable lofts. Shared party walls, restricted parking and conservation rules often shape the plans and the programme.
With that background in mind, here is how we typically handle a new flat roof for homes in Isleworth, from the first visit to the finished result.
Permissions for a new flat roof in Isleworth
The notes below cover England, which is where Isleworth sits. Rules change and every property is different, so we speak to the council before pricing your job.
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
Survey and measure
First, someone visits your home in Isleworth to see the space, take measurements and note anything that could affect the work, such as access or the condition of what is there. There is no charge for this visit.
Quote in writing
After the survey we send a quote for a new flat roof that fixes the price for the scope we've agreed. If you want to change materials or scope, we revise it in writing before anything is booked.
Plan and prepare
We handle the paperwork side: checking whether planning permission or building control approval is needed, submitting applications where they are, and scheduling the trades and materials around your dates.
Finish and handover
Work goes ahead as scheduled and you deal with one contact throughout. When the last trade leaves, we clear and clean the site, talk you through what has been done and pass on any certificates and care instructions.
Why homeowners choose us
Common questions
How long does a flat roof replacement take?
Replacing a typical extension or garage flat roof usually takes one to three days. Stripping and any deck repairs come first, then insulation where agreed, the new membrane and the trims and outlets. GRP needs dry weather and time to cure, and we plan around the forecast. Larger roofs or roofs with many rooflights take longer. We confirm timing with your quote.
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.
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.
How long does a flat roof last?
A well-installed EPDM or GRP flat roof can last 25 years or more, while torch-on felt systems typically last around 15–25 years, depending on quality and exposure. Lifespan depends on correct falls, good detailing at edges and upstands, and keeping outlets clear. Foot traffic, ponding and poor ventilation shorten it. Annual checks help catch small problems early.
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.
Near Isleworth
We cover every part of Isleworth, including TW1, TW3, TW4 and TW5, and nearby Hounslow, Heston and Richmond. Wherever you are within that patch, the survey is free and the quote comes to you in writing.