Planning a Rear Extension in Yeovil: A Homeowner's Guide

Do you actually need planning permission?

Many single storey rear extensions fall under permitted development, meaning you can build without a full planning application. For a detached house you are generally allowed up to 8 metres to the rear, and 6 metres for a semi or terrace, subject to the larger home extension rules and a neighbour consultation.

The catch in Yeovil is that permitted development rights are removed or reduced in conservation areas such as parts of Hendford and around the town centre, and on many newer estates where the original planning conditions restrict changes. If your home is listed, or you live in a village like Montacute or Barwick, assume you will need consent and possibly listed building approval.

• Single storey side or rear: often permitted development
• Two storey rear: usually needs a full application
• Conservation area or listed: consent almost always required
• Always apply for a Lawful Development Certificate as proof for future sale

What local ground and materials mean for your build

Much of Yeovil sits on clay and Yeovil Sands, and gardens on the sloping streets around Preston and Larkhill often need stepped or deeper foundations. If there are mature trees nearby, Building Control may ask for foundations dug to 1.5 metres or more, which adds cost you should budget for early.

Matching materials matters, especially on older properties built in local Ham stone or with render. Reclaimed or cut stone facing costs more than blockwork and render, so decide at design stage whether you want the extension to match seamlessly or to sit as a deliberately modern addition in brick, timber or render.

Realistic costs and timescales

As a rough guide for 2026, a good quality single storey rear extension in the Yeovil area tends to land between 2,000 and 2,800 pounds per square metre for a standard finish, with more for structural glazing, bespoke kitchens or difficult access. A typical 20 square metre kitchen extension might therefore sit somewhere around 40,000 to 55,000 pounds once fitted out, though your figure depends heavily on specification.

On timescale, plan for the build itself to take roughly 10 to 16 weeks for a single storey project, plus the run up. Design, structural calculations and either a planning decision (around 8 weeks) or the permitted development notification all happen before a spade goes in the ground, so starting the paperwork early is the single best thing you can do.

Party walls, drains and neighbours

If you are building near or on a shared boundary, the Party Wall Act may apply and you will need to serve notice on adjoining owners, usually one to two months before work starts. This is common in Yeovil's terraces and semis, and getting it right avoids disputes and delays.

Check where your drains and sewers run too. Building within three metres of a public sewer needs a build over agreement from Wessex Water, which takes time to arrange, so flag it to your builder at the survey rather than discovering it once footings are marked out.