Annexe extensions in Risca: design, approvals and build
From the first sketch to final sign-off, we plan and build annexe extensions in Risca and the surrounding Mid Glamorgan area.
- Guide price in RiscaFrom £51,000 inc VAT
- PlanningUsually a planning application
- Build time16–24 weeks on site
- Postcode districtsNP11
How much does an annexe extension cost in Risca?
Labour and material costs vary across the UK, so for Risca we use our Wales factor (×0.93). The ranges include VAT and exclude design, structural and council fees.
Typical rates in Risca: £1,860 to £3,530 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Studio annexe 25 m² | £51,000 – £64,000 | £55,500 – £70,000 | £69,500 – £88,500 |
| One-bedroom annexe 35 m² | £65,000 – £81,500 | £78,000 – £98,000 | £97,500 – £124,000 |
| Larger annexe 45 m² | £83,500 – £105,000 | £100,000 – £126,000 | £125,500 – £159,500 |
Want a range for your exact size? The guide-price tool takes about a minute.
Extensions in and around Risca
Across NP11, we can visit, measure and advise. The same team covers Caerphilly (6 miles), Blackwood (6 miles), Gelligaer (8 miles), Pontypridd (10 miles), all within easy reach.
Just over the Gwent border, Newport, Gwent is about 5 miles away. In Wales, terraced houses with rear offshoots are common in the towns, while detached houses and bungalows dominate in rural areas.
Planning rules that apply in Risca
In Wales an annexe linked to the house and used by your household is assessed as an extension, but its size usually means a planning application is needed.
In a conservation area, national park, National Landscape or World Heritage Site the permitted development limits are tighter (no side or two-storey extensions without an application). Listed homes need listed building consent, and if permitted development rights have been removed, any extension needs an application.
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).
Who an annexe extension suits
- Multi-generational families
- Relatives who need support close by
- Homes with a large side or rear garden
Accessibility is cheaper to design in than to retrofit. Level access, a 900 mm door width, a level-access shower and space to turn a wheelchair can all be planned into the footprint for little extra cost.
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
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
We produce the drawings and structural design, and manage the approvals so they are in place before work starts.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Annexe extension questions answered
Who do I contract with for an annexe extension in Risca?
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.
How long does an annexe extension take to build in Risca?
On site, typically 16 to 24 weeks once approvals are in place. Before that, allow 10–16 weeks design and approvals.
Do I need building regulations approval in Risca?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
How much does an annexe extension cost?
Our guide range is about £1,860 to £3,530 per m² including VAT. A one-bedroom annexe of about 35 m² is typically £78,000 to £98,000 at standard spec in Risca.
Can the annexe have its own front door?
Yes, many do, but it should still connect to the main house to stay clearly part of it.
Book a free site visit in Risca
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.