Newport and Monmouthshire
Flat-roof rear extensions in Newport and Monmouthshire
Warm flat roofs with lanterns, parapets and long-life membranes. Rear extensions in Newport and Monmouthshire: we cover 6 towns including Newport, Abergavenny and Chepstow, with design, approvals and the build under one contract.
Flat roofs are the usual choice for rear extensions because they stay below first-floor windows and take a lantern neatly. Older terraces near the centre and post-war semis further out are typical of Newport and Monmouthshire. Sloping sites are common in Wales, so floor levels and retaining walls are designed at the start.
How much does a flat-roof rear extension cost in Newport and Monmouthshire?
Guide prices for a flat-roof 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?
Welsh permitted development allows a single-storey rear extension of up to 4 metres in depth and 4 metres in height, subject to boundary and garden-coverage limits. There is no larger-extension prior approval scheme in Wales.
Wales has its own Approved Document L, with targets for walls, roofs, floors and glazing similar to but not identical with England's. Heavily glazed designs are checked with a calculation.
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
How long does a flat roof last?
A well-built single-ply or GRP warm roof typically lasts 25 years or more.
Is a flat roof really flat?
No; it is built to falls so water drains to outlets or gutters.
Can I walk on it?
Not as a balcony without planning permission and a guarding design; it can be accessed for maintenance.
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.