Two-storey extensions for end-of-terrace houses in Wiltshire

Wiltshire at a glance

Nation: England
Price region: South West England
Postcode areas: BA, SN, SP
Towns covered: 14 listed below, plus surrounding villages
Approval route: Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.
Site visits: Free, no obligation

What a two-storey extension for an end-of-terrace house involves

This service suits you if you own an end-of-terrace house with land to the side or a reasonable rear garden.

The main places we list in Wiltshire are Swindon (SN1), Salisbury (SP1), Trowbridge (BA14), Chippenham (SN15), Melksham (SN12) and Warminster (BA12). We cover the villages in between too.

Guide price in South West England

A guide price for Wiltshire: around £88,500–£119,000 for a 3 m × 7 m footprint on two floors (42 m² of new floor space). That works out at £2,110–£2,830 per m² of new floor space, including VAT at 20%. These are guides, not quotes. Ground conditions, steelwork and access can move the figure either way.

Spec	Per m²	Typical project
Essential	£1,940–£2,610 per m²	£81,500–£109,500
Standard	£2,110–£2,830 per m²	£88,500–£119,000
Premium	£2,530–£3,400 per m²	£106,500–£143,000

Rules in England

In England, a two-storey side extension on an end-of-terrace house always needs planning permission, costing £548 (or £575 for applications made from 8 December 2026). A two-storey rear extension can be permitted development within 3 m of the original rear wall and 7 m from the rear boundary. On a corner plot, nothing can go beyond a side wall that fronts a highway under permitted development.

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.

The Party Wall etc. Act 1996 applies, so notices may be needed for work on or near a shared wall or boundary.

Getting the design right

Continuing the terrace roof

A side extension on an end-of-terrace house usually continues the roofline of the row, so the pitch, eaves height and tiles must match. A small step down in the ridge and a set-back at the front often help the extension read as an addition rather than an extra house.

Corner plots

Many end-of-terrace houses sit on corners, where the side wall faces a road. In England nothing can be built beyond a side wall that fronts a highway under permitted development, and councils guard open corners, so we keep a gap to the pavement and design the side wall as a second front.

How we work in Wiltshire

Free site visit
We visit your home in Wiltshire, look at the structure, access and boundaries, and talk through what you want the new rooms to do.
Design and approvals
We draw the extension and check it against the rules for England, then apply for planning permission or a certificate of lawfulness, whichever fits.
Fixed price in writing
With approved drawings and calculations, we give you a fixed build price and a programme you can plan around.
Build and sign-off
Vetted teams working under S&K build the extension, and we arrange the building control completion certificate at the end.

Towns we cover in Wiltshire

Two-storey extensions for end-of-terrace houses in Wiltshire: questions

How much does a two-storey extension for an end-of-terrace house cost in Wiltshire?

In South West England our guide is £2,110–£2,830 per m² including VAT, so about £88,500–£119,000 for a 3 m × 7 m footprint on two floors (42 m² of new floor space). Essential and Premium specs move that by roughly 8% down or 20% up.

Can I build a two-storey side extension on a corner plot?

Often, but it needs planning permission and careful design. Councils protect the openness of corners and the view along the road, so they usually expect a gap to the pavement, a set-back from the front and a side wall with windows rather than a blank wall. We check local guidance and nearby examples first.

Are old terrace foundations strong enough to extend next to?

Usually, but they need checking. Older terraces often have shallow brick footings, and a new two-storey extension sits on deeper, modern foundations alongside them. The structural engineer designs the junction so the two can move slightly without cracking, and we dig trial holes to see what is there before the design is fixed.

Will my end-of-terrace extension look like a new house on the end?

It should not, if it is designed well. A slightly lower ridge, a set-back from the front wall and a different front door position help it read as an extension. Councils often ask for this to avoid an extension that looks like an extra terraced house.

Will I need planning permission in Wiltshire?

Wiltshire is in England. Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.

Neighbouring areas

All extension services in Wiltshire · About two-storey extensions for end-of-terrace houses