Side extensions in Merthyr Tydfil: design, approvals and build
We design and build side extensions for houses in Merthyr Tydfil, with a written price once the survey and design are done and one point of contact throughout.
- Guide price in Merthyr TydfilFrom £20,000 inc VAT
- PlanningSingle storey can be permitted development
- Build time10–18 weeks on site
- Postcode districtsCF47, CF48
When a side extension makes sense
- Homes needing a utility, study or ground-floor bedroom
- Houses where the rear garden is small
- Detached and semi-detached houses with side land
Will the council need to approve it?
In Wales a single-storey side extension can be permitted development if it is no more than 4 m high and no wider than half the width of the original house, and it must not come closer to a highway than the existing side wall. Larger side extensions need planning permission.
Homes in conservation areas, national parks, National Landscapes (AONBs) and World Heritage Sites have tighter rules, so we always check the property's status and planning history before design starts.
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).
Working in Merthyr Tydfil
Site visits are available across Merthyr Tydfil (CF47, CF48). Neighbouring towns we cover include Aberdare (4 miles), Rhondda (7 miles), Gelligaer (8 miles), Blackwood (9 miles).
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.
How much does a side extension cost in Merthyr Tydfil?
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 Merthyr Tydfil: £1,630 to £3,160 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 2.5 m × 5 m 12 m² | £20,000 – £25,000 | £22,500 – £30,000 | £29,000 – £38,000 |
| 3 m × 6 m 18 m² | £29,000 – £35,500 | £34,000 – £44,500 | £43,500 – £57,000 |
| 3 m × 8 m 24 m² | £39,000 – £47,000 | £45,500 – £59,500 | £58,000 – £76,000 |
Want a range for your exact size? The guide-price tool takes about a minute.
How the project works
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
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
Fixed written price
The price is fixed in writing once the design is settled, with a clear programme and payment stages.
Build and sign-off
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Common questions 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.
Will my neighbours in Merthyr Tydfil 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.
Who do I contract with for a side extension in Merthyr Tydfil?
Your contract is with S&K Property Investments and Improvement Ltd, which designs and manages the project and the build teams who carry it out.
Can I build over my driveway?
Yes, if the foundations work and you keep any parking the council requires. Drains and services under drives are common, so we check before design.
How much does a side extension cost?
Our guide range is about £1,630 to £3,160 per m² including VAT, depending on specification, so a standard 18 m² single-storey side extension lands around £34,000 to £44,500 in Merthyr Tydfil.
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.