First-floor extensions in Andover

Before you start in Andover, here's what applies.

Postcode districts: RG28, SO20, SP10 and SP11
County / area: Hampshire, England
Price region: South East England
Guide price: £27,500–£40,000 (£1,980–£2,860 per m²)
Approval route: It may be permitted development if it goes no more than 3 m beyond the original rear wall (counting any single-storey part) and stays 7 m from the rear boundary; otherwise it needs planning permission.
Nearest towns: Tidworth (7.5 miles), Bulford (11.6 miles), Winchester (12.6 miles)
Distance to Southampton: about 21.6 miles
First visit: Free, no obligation

About a first-floor extension

A first-floor extension is a new upstairs room built on top of an existing single-storey part of your house, such as a rear kitchen extension, a utility or a side annexe. It adds a bedroom, bathroom or study without enlarging the footprint. Whether it works depends mainly on whether the walls and foundations below can carry the extra load.

We cover postcode districts RG28, SO20, SP10 and SP11 in and around Andover, along with neighbouring Tidworth, Bulford and Winchester.

What it costs in Andover

Our guide for South East England is £1,980–£2,860 per m² including VAT. On a project with 4 m × 3.5 m of new first-floor space (14 m²), that puts a first-floor extension in Andover at roughly £27,500–£40,000. The fastest way to a firmer number is a free site visit, after which we price the design stage in writing.

Spec	Per m²	4 m × 3.5 m of new first-floor space (14 m²)
Essential	£1,820–£2,630 per m²	£25,500–£37,000
Standard	£1,980–£2,860 per m²	£27,500–£40,000
Premium	£2,380–£3,430 per m²	£33,500–£48,000

Planning and building regulations in Andover

In England, adding a first floor turns a single-storey extension into one of more than one storey. To be permitted development, the extension as a whole must go no more than 3 m beyond the rear wall of the original house and stay at least 7 m from the rear boundary, with matching materials and roof pitch. Over a side extension it always needs planning permission, costing £548 (or £575 for applications made from 8 December 2026).

Approval in England: Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026). Councils should decide householder applications within 8 weeks of validation.

Building regulations: Building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end.

Design points for Andover homes

Can the existing structure take it?

Many single-storey extensions were built with foundations, walls and lintels sized for one storey. We find out what is there with trial holes and, where available, the original building control drawings. The engineer then decides whether to reuse, strengthen or rebuild parts of the structure.

Matching the roofline

A first-floor extension often changes how the back or side of the house looks more than the original single storey did. Matching the main roof pitch and materials, and keeping the ridge below the main ridge, usually gives the best result and is expected for permitted development in England.

How we'd run your project

Look at the house
We start in Andover with a free visit: measurements, photos, a look at the loft and drains, and a frank chat about budget.
Plans, then approval
Measured survey, design, then the right approval route for your house. We explain each step before we take it.
Technical design
We prepare the building regulations drawings, structural calculations and specification so the build price can be fixed.
Build it
The new structure goes up first, then we open into the house, finish inside and get the completion certificate.

Questions about first-floor extensions in Andover

Which postcodes do you cover around Andover?

We cover Andover (RG28, SO20, SP10 and SP11) and nearby places including Tidworth, Bulford and Winchester, plus the rest of Hampshire. The first site visit is free.

Do I need planning permission for a first-floor extension in Andover?

Andover is in England, so England planning rules apply. It may be permitted development if it goes no more than 3 m beyond the original rear wall (counting any single-storey part) and stays 7 m from the rear boundary; otherwise it needs planning permission. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.

Who handles building regulations for a project in Andover?

We handle it as part of the project. What's needed in England: building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end. We prepare the drawings and the engineer's calculations, book the inspections and pass you the completion paperwork at the end.

Will the first-floor extension match my house?

It should, and in England matching materials and roof pitch is a condition of permitted development. We match brick, tile, mortar colour and window style where we can, and tell you at the design stage if an exact brick match is not available, so you can choose between the closest match and render or cladding.

What happens to the room below while the first floor is built?

The old roof is removed, so the room below is exposed for a short period. We fit temporary weather protection, plan the work so the roof comes off only when the new structure is ready, and agree with you which rooms will be out of use and for roughly how long.

Nearby

The same service in neighbouring towns:

Other extensions in Andover

All two-storey extension services in Andover · First-floor extensions across Hampshire

Send us your postcode and a few details. We'll get back to you to arrange a visit and talk through your options.