Flat roof extensions in Caerphilly
We design and build flat roof extensions for houses in Caerphilly, with a written price once the survey and design are done and one point of contact throughout.
- Guide price in CaerphillyFrom £19,500 inc VAT
- PlanningWelsh permitted development rules (rear up to 4 m)
- Build time10–16 weeks on site
- Postcode districtsCF83
When a flat roof extension makes sense
- Modern and 1930s onwards houses
- Extensions under first-floor windows where a pitch will not fit
- Homeowners who want maximum light from above
Height is often what decides a flat roof. Under first-floor windows, a pitched roof may not fit at all; a flat roof keeps the extension low while still giving a good ceiling height inside.
Covering Caerphilly
Across CF83, we can visit, measure and advise. Nearby, we also take on projects in Risca (6 miles), Pontypridd (6 miles), Gelligaer (6 miles), Blackwood (6 miles).
Just over the South Glamorgan border, Cardiff is about 7 miles away. In Wales, terraced houses with rear offshoots are common in the towns, while detached houses and bungalows dominate in rural areas.
Do I need planning permission in Caerphilly?
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 Caerphilly address depends on its history and any designations, which is why we check it at the first visit.
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).
Guide prices for Caerphilly
These guide figures apply our Wales adjustment (×0.93) to national rates. They include VAT at 20% and cover the build itself; design and council fees are listed separately.
Typical rates in Caerphilly: £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 |
For a figure based on your own dimensions, use our guide-price tool.
Our process, step by step
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
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
The build is managed from start to finish, inspected at each stage and signed off on completion.
Your questions about a flat roof extension in Caerphilly
Do you cover all of Caerphilly?
Yes. We cover Caerphilly and the surrounding parts of Mid Glamorgan. Site visits are free and there is no obligation.
Do I need building regulations approval in Caerphilly?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Will my neighbours in Caerphilly be involved?
If a planning application is needed, the council notifies neighbours. If the work is on or near a shared boundary, party wall notices may also be needed.
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.
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.
Book a free site visit in Caerphilly
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.