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.
Whether you live in one of the larger towns, such as Cardiff, Barry, Penarth and Llantwit Major, or somewhere quieter in South Glamorgan, the way we handle a new flat roof is identical. We survey, agree the specification with you, and confirm a fixed price on paper. Everything is planned under the regulations in force in Wales, and guide costs in Wales sit at £1,850–£4,100 with VAT.
- Guide price
- £1,850–£4,100 inc VAT
- Time on site
- 1–3 days for most roofs
- Planning rules
- Wales
- Price level
- About 8% below the national guide
- Towns listed
- 4
- Survey
- Free, with a written quote
Flat roofs prices in South Glamorgan
Use the table to gauge the cost of a new flat roof in South Glamorgan before we visit. Figures include VAT and are scaled for Wales, coming out about 8% below the national guide, which gives £1,850–£4,100 overall. After a free survey, you receive a fixed written price.
| Type of job | What it usually involves | Guide in South Glamorgan |
|---|---|---|
| Small roof (up to 8m²) | A dormer, bay, porch or small garage roof re-covered in EPDM or GRP. | £750–£1,850 |
| Extension or garage (15–25m²) | A typical extension or single garage roof stripped and re-covered. | £1,850–£4,100 |
| Large or new warm roof | Larger roofs, or roofs needing a new deck and insulation build-up. | £3,700–£8,300 |
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
- Number of rooflights, pipes and upstands to detail
What do you get?
- Survey of the covering, deck, falls, upstands and drainage
- Stripping and disposal of the old roof covering
- Replacement of rotten or soft deck boards
- 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 South Glamorgan
Cardiff has large areas of bay-fronted Victorian and Edwardian terraces in districts such as Roath, Canton and Cathays, plus interwar suburbs, post-war estates and modern flats around Cardiff Bay. Penarth has Victorian villas, Barry mixes terraces with newer estates, and Vale of Glamorgan villages are often built of local limestone.
Terraces commonly suit loft conversions, side-return and rear extensions, and bay window renewal. Suburban semis take side extensions and driveways, and stone village homes need lime-based repairs.
Mild but wet, with coastal exposure along the Severn estuary and Bristol Channel affecting render, roofline and windows.
Do you need permission in South Glamorgan?
England, Wales, Scotland and Northern Ireland each handle planning a little differently. South Glamorgan comes under Wales, covered below, and we raise any questions with the council before your quote is finalised.
Re-roofing with similar materials does not usually need planning permission in Wales, except on listed buildings or where a conservation area restricts materials.
Building Regulations in Wales apply to major re-roofing, including insulation upgrades. 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
A free survey comes first. It gives us what we need to price a new flat roof properly, including dimensions, existing materials and access for deliveries, and gives you the chance to ask anything you like.
Your fixed price
You get the price in writing, itemised so you can see where the money goes. As long as the specification stays the same, that is the price you pay for a new flat roof.
Getting ready
With the quote agreed, we book the work in and handle preparation: permissions where needed, building control notifications, material orders and access arrangements for your South Glamorgan property.
On site to finish
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.
How we work
Questions about a new flat roof in South Glamorgan
Which postcodes in South Glamorgan do you cover?
We cover CF10, CF62, CF64 and CF61, along with the rest of South Glamorgan. If your postcode is not listed, get in touch anyway: our coverage is UK-wide, and we can usually arrange a survey wherever you live. Enter your postcode in the guide-price tool or contact form and we will confirm.
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.
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.
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.
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.
Towns in South Glamorgan
Choose your town from the list to see how we price and plan a new flat roof in your part of South Glamorgan, including typical time on site.