Newport and Monmouthshire
Rear extensions for semi-detached houses in Newport and Monmouthshire
Single or two-storey extensions for semi-detached houses, with side access and one party wall. We design and build rear extensions across Newport and Monmouthshire, from Newport and Abergavenny to Chepstow, covering single-storey kitchen extensions, two-storey additions, side returns and wraparounds.
In Newport we measure the attached neighbour's extension at the survey, because it often sets the sensible depth for yours. Newport and Monmouthshire has Victorian terraces near the centre and semis further out. Welsh permitted development allows up to 4 metres at the rear for many houses.
How much does a semi-detached rear extension cost in Newport and Monmouthshire?
Guide prices for a semi-detached rear extension in Newport and Monmouthshire start from our Wales rate of £1,770–£2,880 per square metre, including VAT. Prices in Wales sit below our West Midlands baseline; sloping sites are the main variable.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £21,000–£34,500 |
| 4 m wide × 5 m deep (20 m²) | £35,500–£57,500 |
| 4 m wide × 6 m deep (24 m²) | £42,500–£69,000 |
Your written price follows a measured survey and an agreed design, so it reflects your house, not an average.
Do you need planning permission in Newport and Monmouthshire?
In Wales a single-storey rear extension can often be permitted development if it projects no more than 4 metres beyond the rear wall and is no more than 4 metres high. Wales has no prior approval route for deeper extensions, so anything bigger needs a householder planning application.
Welsh rules allow a two-storey rear extension without an application only where the ground floor is no deeper than 4 metres, the upper floor no deeper than 3 metres and at least 10.5 metres remains to the rear boundary. Most homeowners still apply for householder planning permission.
Conservation areas, National Parks and National Landscapes restrict permitted development in Wales, and listed buildings need listed building consent.
Where in Newport and Monmouthshire do we work?
FAQ
Questions people ask
Can I match pebbledash or render?
Yes. Many semis are refinished with new render across the whole back elevation so old and new match.
Single or two-storey on a semi?
Two-storey if you need bedrooms, single-storey if you need a bigger kitchen. Planning risk is lower for single-storey.
What if my neighbour has already extended?
That can make a matching depth easier to justify. We measure theirs at the survey.
Do you cover all of Newport and Monmouthshire?
We cover 6 towns and districts in Newport and Monmouthshire, including Newport, Abergavenny and Chepstow.
Who builds the extension?
Vetted building teams working under contract to us; your contract is with S&K Property Investments and Improvement Ltd.