Single-storey extensions in Cornwall

Covering Cornwall

Our coverage across Cornwall includes Redruth, Falmouth, St Austell and Truro.

Because Cornwall covers a wide area, we confirm availability after the first call and include any travel costs in the written quote rather than adding them later.

Homes in the South West

In the South West, matching local stone, render or slate is often the main design question, and conservation areas and listed buildings are common in historic towns.

What is included in a single-storey extension in Cornwall?

We design the extension around how you use the house: where the light comes from, how the new room joins the old one, and what happens to the drains and the garden. The structure is built in brick or block to match the house, finished with a flat roof and lantern or a pitched roof, then insulated, plastered and handed back ready to decorate.

Measured survey and design drawings
Building control application and inspections
Foundations, drainage and structural steel

How much should I budget for a single-storey extension?

Use these ranges to budget for single-storey extensions; the survey turns them into a fixed price for the agreed specification.

Single-storey extensions	Guide price incl. VAT
Standard specification	£2,600 to £3,000 per m²
Good specification	£3,000 to £3,500 per m²
High specification	£3,500 to £4,000 per m²

How is a single-storey extension approved in Cornwall?

In England we deal with the council’s planning team for permission or a lawful development certificate, with building control (the council or a registered building control approver) for inspections, and with neighbours under the Party Wall etc. Act 1996 where it applies.

In England a single-storey rear extension can often go ahead under permitted development: up to 3 m deep on an attached house or 4 m on a detached one, no higher than 4 m, with eaves no higher than 3 m within 2 m of a boundary. Deeper extensions, up to 6 m or 8 m, need prior approval from the council first.

What should Cornwall homeowners check first?

Building on or near a shared boundary usually means serving a party wall notice in England and Wales.
Large glazed areas need to meet energy rules, which can shape the size of doors and rooflights.

From first call to completion

Start with a conversation. A short call or the online form is enough for us to understand what you want to build.
We visit and measure. A surveyor checks the house, the boundaries and the ground, and discusses what is realistic.
Design and fixed price. You get drawings and a written price for the agreed specification before anything is ordered.
We build it. Work follows an agreed programme, with inspections at each stage and a final sign-off.

Questions about a single-storey extension in Cornwall

How long does a single-storey extension take to build?

The build itself usually takes 10 to 16 weeks once work starts on site. Design, approvals and ordering usually add 6 to 12 weeks before that.

Can we stay in the house during the build?

Usually yes. We keep the existing house closed off from the works until the knock-through near the end, and agree a temporary kitchen set-up with you if the kitchen is affected.

How do I get a price for single-storey extensions in Cornwall?

Use the guide price tool for a ballpark figure, then book a visit for a fixed written price for the agreed specification.

Also covering

Learn more about single-storey extensions, or see every project we cover in Cornwall.