Flat roof extensions across Merthyr Tydfil
A flat roof extension in Merthyr Tydfil starts with the right design and the right approval route. We take care of both, then build it with our own project management.
- Guide price in Merthyr TydfilFrom £19,500 inc VAT
- PlanningWelsh permitted development rules (rear up to 4 m)
- Build time10–16 weeks on site
- Postcode districtsCF47, CF48
Guide prices for Merthyr Tydfil
Labour and material costs vary across the UK, so for Merthyr Tydfil we use our Wales factor (×0.93). The ranges include VAT and exclude design, structural and council fees.
Typical rates in Merthyr Tydfil: £1,630 to £3,120 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m 12 m² | £19,500 – £23,000 | £22,500 – £29,500 | £29,000 – £37,500 |
| 4 m × 5 m 20 m² | £32,500 – £38,500 | £38,000 – £48,500 | £48,000 – £62,500 |
| 5 m × 6 m 30 m² | £48,500 – £57,500 | £57,000 – £73,000 | £72,500 – £93,500 |
Want a range for your exact size? The guide-price tool takes about a minute.
Planning and approvals in Merthyr Tydfil
In Wales a single-storey rear extension can usually project up to 4 m beyond the rear wall without a planning application, if it is no more than 4 m high, keeps eaves to 3 m and overall height to 4 m within 2 m of a boundary, and covers no more than half the land around the original house. Wales has no larger home extension prior approval scheme.
The planning position for a specific Merthyr Tydfil address depends on its history and any designations, which is why we check it at the first visit.
Building regulations approval is separate from planning. Wales has its own building regulations and approved documents; the council or a registered building control approver checks the plans, inspects the work and issues a completion certificate.
The Party Wall etc. Act 1996 applies in Wales as in England: notice must be served before work to a shared wall, building on the boundary, or excavating close to a neighbour's foundations.
Applications are decided by the local planning authority (your county or county borough council, or the national park authority).
Extensions in and around Merthyr Tydfil
Our survey diary covers Merthyr Tydfil, including CF47, CF48. The same team covers Aberdare (4 miles), Rhondda (7 miles), Gelligaer (8 miles), Blackwood (9 miles), all within easy reach.
Just over the Gwent border, Ebbw Vale is about 8 miles away. Welsh housing ranges from stone terraces in the valleys to render-and-slate houses and modern estates, and the Welsh planning rules differ from England's in several places.
What is included
- Falls and outlets designed to drain properly
- Parapets or edge trims and flashings to the house
- Lanterns or rooflights with upstands
- Membrane choice: single-ply, EPDM or GRP
- Warm-roof design with insulation above the deck
From first visit to completion
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
Fixed written price
You receive a written, itemised price and programme. Nothing starts until you are happy with it.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Your questions about a flat roof extension in Merthyr Tydfil
Do you cover all of Merthyr Tydfil?
Yes. We cover Merthyr Tydfil and the surrounding parts of Mid Glamorgan. Site visits are free and there is no obligation.
How long does a flat roof extension take to build in Merthyr Tydfil?
On site, typically 10 to 16 weeks once approvals are in place. Before that, allow 4–12 weeks design and approvals.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Merthyr Tydfil, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Can I walk on a flat roof extension?
Only for maintenance unless it is designed as a terrace. A roof terrace or balcony needs planning permission and a different structure.
Are flat roof extensions cheaper?
Usually slightly, because there is less roof structure and no tiles. Our guide range is about £1,630 to £3,120 per m² including VAT.
Book a free site visit in Merthyr Tydfil
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.