Cardiff bedroom extensions, designed and built
Cardiff homeowners can use us for the whole bedroom extension project: survey, design, planning or permitted development checks, building regulations and the build itself.
- Guide price in CardiffFrom £24,000 inc VAT
- PlanningUsually a planning application
- Build time14–22 weeks on site
- Postcode districtsCF5, CF10, CF11, CF14, CF23
What is included
- Structure, roof, insulation and finish
- Fire safety: escape windows and smoke alarms to building regulations
- En-suite drainage and ventilation design
- Layout options: two-storey, over-garage or ground floor
- Heating extended to the new rooms
- Planning drawings and application
Local to Cardiff
We cover Cardiff and the postcode districts CF5, CF10, CF11, CF14, CF23, CF24. We also work in nearby Penarth (3 miles), Barry (7 miles), Cowbridge (12 miles).
Caerphilly, in Mid Glamorgan, is roughly 7 miles from Cardiff and also on our list. 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 bedroom extension cost in Cardiff?
Prices below are for Cardiff, using the Wales factor of ×0.93. They are guide ranges including VAT for the build only, not a quote.
Typical rates in Cardiff: £1,490 to £2,980 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| One bedroom 12 m² | £24,000 – £29,500 | £24,000 – £31,500 | £26,500 – £36,000 |
| Bedroom and en-suite 18 m² | £26,500 – £33,000 | £31,500 – £41,500 | £40,000 – £54,000 |
| Two rooms 30 m² | £44,500 – £54,500 | £53,000 – £68,500 | £66,500 – £89,500 |
Want a range for your exact size? The guide-price tool takes about a minute.
Will the council need to approve it?
In Wales a rear extension of more than one storey can be permitted development only if the ground floor projects no more than 4 m, the upper floor no more than 3 m, it stays at least 10.5 m from the rear boundary and it is not in a conservation area, national park, National Landscape or World Heritage Site. Anything larger needs a planning application to the council.
Before any drawing is finalised we check whether the house is listed, in a conservation area or subject to an Article 4 direction.
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.
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.
Applications are decided by the local planning authority (your county or county borough council, or the national park authority).
What happens next
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
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
Fixed written price
You receive a written, itemised price and programme. Nothing starts until you are happy with it.
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 Cardiff
Who do I contract with for a bedroom extension in Cardiff?
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 see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Cardiff, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Do I need building regulations approval in Cardiff?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Does an en-suite need a window?
No, but it needs mechanical extraction that meets the building regulations. We design the duct route at the drawing stage.
Will a new bedroom need planning permission?
Upstairs additions usually do. Ground-floor rooms may fall within permitted development, depending on size and position.
Book a free site visit in Cardiff
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.