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.
Homeowners in Windsor usually consider a new flat roof for one of a few reasons: something has worn out, the house no longer suits the way they live, or they are getting it ready to sell. We visit, agree a specification and put a fixed price in writing. Most jobs like this take 1–3 days for most roofs, and we work across Berkshire, including Slough, Egham and Staines.
- Guide price
- £2,200–£5,000 inc VAT
- Time on site
- 1–3 days for most roofs
- Postcodes
- SL4
- Planning rules
- England
- Local area
- Windsor and Maidenhead
- Survey
- Free, with a written quote
Flat roofs prices in Windsor
Below is a breakdown of typical costs for a new flat roof in Windsor. Because rates in the South East are about 12% above the national guide, the overall guide comes to £2,200–£5,000, 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 Windsor |
|---|---|---|
| Small roof (up to 8m²) | A dormer, bay, porch or small garage roof re-covered in EPDM or GRP. | £900–£2,200 |
| Extension or garage (15–25m²) | A typical extension or single garage roof stripped and re-covered. | £2,200–£5,000 |
| Large or new warm roof | Larger roofs, or roofs needing a new deck and insulation build-up. | £4,500–£10,000 |
Your price depends mostly on:
- Roof area and access to the roof
- Covering system: EPDM, GRP or torch-on felt
- Condition of the deck and joists underneath
- Insulation upgrades and changes to roof height at edges
What does the job include in Windsor?
- 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
- Rooflights refitted or replaced where required
Local housing and a new flat roof
Reading's Victorian terraces often show the town's patterned red and silver-grey brickwork, while Windsor, Maidenhead and Newbury mix Georgian, Victorian and Edwardian houses. Bracknell grew as a post-war new town with planned estates, Slough has a great deal of interwar and post-war housing, and newer developments sit on the edge of most towns.
Period terraces lend themselves to side-return extensions and dormer lofts; post-war and new-town homes often need replacement windows, roofline renewal and extra space. Larger detached houses commonly take on kitchen extensions, bifold doors and landscaping.
These patterns matter for a new flat roof: older walls, roofs and floors in Windsor can need different materials or extra preparation compared with newer homes.
Permissions for a new flat roof in Windsor
For anyone in Windsor, 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.
How does the job run?
A visit to your home
It starts with a survey at the property, free of charge. We check condition, access and services, ask how you want the finished result to look, and answer any questions you have about a new flat roof.
Your fixed price
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.
Finish and handover
On site, the agreed plan is followed and any change is put in writing first. At completion we do a final clean, go through the snagging list with you and leave you with the relevant documents.
How we work
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.
Why does water sit on my flat roof?
Ponding water on a flat roof is usually caused by inadequate falls, sagging joists, a deck that has dipped or blocked outlets. Small puddles that dry within a day or two are not always a problem, but standing water speeds up wear and finds any weakness. A new roof can be laid on firring strips or tapered insulation to create proper falls. We check falls during the survey.
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.
What happens at the survey?
We visit your home at a time that suits you, look at the area involved, take measurements and check access, condition and any services that might be affected. We talk through what you want from a new flat roof, explain the options and answer questions. There is no charge and no obligation; afterwards we send a written quote.
Can you combine a new flat roof with other work?
Yes. Because we manage several trades under one contract, we can plan a new flat roof alongside other work on your Windsor home, such as new windows with rendering, or a kitchen refit with an extension. Combining jobs can reduce repeat set-up such as scaffolding, skips and access, and every element is listed and priced in the same written quote.
Nearby towns
Windsor and its SL4 postcodes are part of our coverage. Homeowners in Slough, Egham and Staines can also book a free survey with us and receive a written price for their job.