Single-storey extensions in Horsham

Covering Horsham

Alongside Horsham, we also cover Crawley, Horley (11 miles to the north-east) and Haywards Heath.

Homes in the South East

Housing across the South East mixes inter-war semis, post-war estates and older cottages in villages and market towns, so rear and side extensions, hip-to-gable lofts and garage conversions all come up regularly.

What do you get with a single-storey extension?

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
Planning or lawful development certificate where needed
First-fix and second-fix electrics, plastering and making good

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

What single-storey extensions typically cost. These are guide ranges; the written quote for your house replaces them.

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

Planning and building rules in Horsham

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 I think about before starting?

Drains under the footprint may need diverting or a build-over agreement with the water company.
Building on or near a shared boundary usually means serving a party wall notice in England and Wales.

From first call to completion

Tell us about the project. Call, use the guide price tool or send the form with a few photos and a postcode.
We visit and measure. A surveyor checks the house, the boundaries and the ground, and discusses what is realistic.
Drawings, approvals, written quote. We prepare the design, apply for the approvals it needs, and give you a fixed price in writing.
We build it. Work follows an agreed programme, with inspections at each stage and a final sign-off.

Single-storey extensions: common questions

Do you need to dig up the drains?

Sometimes. If a public sewer runs under the extension, the water company has to agree a build-over or a diversion. We check this at survey stage.

Will the brick match?

We source the closest available match for colour, size and texture and agree a sample panel with you before laying.

Can you visit a house in Horsham to quote?

Yes. After a short call we arrange a site visit to measure up and agree what the design needs to do, then send a written price.

Other towns nearby

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