Home office extensions in Monmouth
We design and build home office extensions for houses in Monmouth, with a written price once the survey and design are done and one point of contact throughout.
- Guide price in MonmouthFrom £14,500 inc VAT
- PlanningWelsh permitted development rules (rear up to 4 m)
- Build time8–12 weeks on site
- Postcode districtsNP25

Planning and approvals in Monmouth
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.
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.
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).
What is included
- Window and rooflight placement to avoid screen glare
- Sound insulation to the adjoining rooms
- Heating or cooling sized for the room
- Layout for desk, storage and video calls
- Data cabling and plenty of sockets
Guide prices for Monmouth
Prices below are for Monmouth, using the Wales factor of ×0.93. They are guide ranges including VAT for the build only, not a quote.
Typical rates in Monmouth: £1,720 to £3,160 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 2.5 m × 3.2 m 8 m² | £14,500 – £18,000 | £15,500 – £20,500 | £20,000 – £25,500 |
| 3 m × 3.6 m 11 m² | £18,500 – £23,000 | £21,500 – £28,000 | £27,500 – £35,000 |
| 3 m × 5 m 15 m² | £25,500 – £31,000 | £29,500 – £38,000 | £37,500 – £47,500 |
For a figure based on your own dimensions, use our guide-price tool.
Extensions in and around Monmouth
Across NP25, we can visit, measure and advise. Neighbouring towns we cover include Chepstow (11 miles), Abergavenny (12 miles), Pontypool (15 miles), Cwmbran (16 miles).
Risca, in Mid Glamorgan, is roughly 21 miles from Monmouth and also on our list. In Wales, terraced houses with rear offshoots are common in the towns, while detached houses and bungalows dominate in rural areas.
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
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
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
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.
Home office extension questions answered
Do I need building regulations approval in Monmouth?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
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.
How long does a home office extension take to build in Monmouth?
On site, typically 8 to 12 weeks once approvals are in place. Before that, allow 4–10 weeks design and approvals.
How much does a home office extension cost?
Our guide range is about £1,720 to £3,160 per m² including VAT. An 11 m² standard-spec office is typically £21,500 to £28,000 in Monmouth.
Is an attached office better than a garden office?
An attached office shares the house heating and broadband, adds floor area to the home, and needs no garden path in the rain. A garden building can be cheaper and quicker but is a separate structure.
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.