Kitchen Extension Cost in Wales: 2026 Price Guide

A single-storey rear kitchen extension is one of the most popular home improvement projects across Wales, including in Cardiff, Swansea, Newport and Wrexham - it's usually the difference between a cramped galley kitchen and a proper kitchen-diner opening onto the garden.

Typical costs

• Small extension (up to 15m²): roughly £20,000-£35,000
• Medium extension (15-25m²): roughly £35,000-£55,000
• Larger or wraparound extension (25m²+): £55,000 upwards

These figures are a UK-wide guide, not a quote - actual costs vary by exact location, with city centres and larger towns generally at the upper end and smaller towns nearer the lower end. Bifold or sliding doors, roof lanterns, underfloor heating and a higher-spec kitchen will all add to the total.

What affects the price

Terraced and semi-detached houses without side access - common in the older streets of many towns across Wales - typically cost more to extend than a detached property, since materials have to be carried through the house and skips have to sit on the road. Older housing stock can also mean shallower original foundations, which a structural engineer may need to address as part of the extension.

Do you need planning permission?

Many single-storey rear extensions fall under permitted development rather than needing a full planning application, but there are limits, and planning permission and permitted development rights in Wales have been set separately from England since 2016, so always check the specific rules with your local council rather than assuming an England-based guide applies.