Annexe extensions in Monmouth
From the first sketch to final sign-off, we plan and build annexe extensions in Monmouth and the surrounding Gwent area.
- Guide price in MonmouthFrom £51,000 inc VAT
- PlanningUsually a planning application
- Build time16–24 weeks on site
- Postcode districtsNP25
Do I need planning permission in Monmouth?
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.
Before any drawing is finalised we check whether the house is listed, in a conservation area or subject to an Article 4 direction.
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).
Is an annexe extension right for your house?
- Relatives who need support close by
- Multi-generational families
- Homes with a large side or rear garden
Local to Monmouth
Site visits are available across Monmouth (NP25). The same team covers Chepstow (11 miles), Abergavenny (12 miles), Pontypool (15 miles), Cwmbran (16 miles), all within easy reach.
Just over the Mid Glamorgan border, Risca is about 21 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.
Annexe extension prices in Monmouth
For Monmouth we adjust our national guide rates by ×0.93, the factor we use for Wales. Figures include VAT; your written quote after the survey replaces them.
Typical rates in Monmouth: £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.
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
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
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
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Annexe extension questions answered
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Monmouth, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Who do I contract with for an annexe extension in Monmouth?
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 Monmouth?
On site, typically 16 to 24 weeks once approvals are in place. Before that, allow 10–16 weeks design and approvals.
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 Monmouth.
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 Monmouth
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.