Bath side extensions, designed and built
Bath homeowners can use us for the whole side extension project: survey, design, planning or permitted development checks, building regulations and the build itself.
- Guide price in BathFrom £22,000 inc VAT
- PlanningSingle storey can be permitted development
- Build time10–18 weeks on site
- Postcode districtsBA1, BA2
Planning and approvals in Bath
In England a single-storey side extension can be permitted development if it is no more than 4 m high and no wider than half the width of the original house. Two-storey side extensions, and any side extension on designated land such as a conservation area, need a householder planning application.
The planning position for a specific Bath address depends on its history and any designations, which is why we check it at the first visit.
Building over or within 3 m of a public sewer needs the water company's consent, usually through a build-over agreement, before the foundations go in.
Applications are decided by the local planning authority (your district, borough or unitary council).
What we take care of
- Survey, design and street-view drawings
- Structure, roof tied into the house
- New openings through the side wall
- Planning route checked or application made
- Foundations near boundaries and any drains
- Windows, doors and finishes to match
Extensions in and around Bath
We cover Bath and the postcode districts BA1, BA2. We also work in nearby Keynsham (6 miles), Frome (10 miles), Nailsea (18 miles), Portishead (19 miles).
In the South West, local stone, render and brick vary from town to town, so matching materials is a big part of designing an extension that looks right.
What should I budget for a side extension in Bath?
Prices below are for Bath, using the South West England factor of ×1.02. They are guide ranges including VAT for the build only, not a quote.
Typical rates in Bath: £1,780 to £3,470 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 2.5 m × 5 m 12 m² | £22,000 – £27,000 | £25,000 – £32,500 | £31,500 – £42,000 |
| 3 m × 6 m 18 m² | £32,000 – £39,000 | £37,500 – £49,000 | £47,500 – £62,500 |
| 3 m × 8 m 24 m² | £42,500 – £51,500 | £50,000 – £65,000 | £63,500 – £83,500 |
Try the guide-price tool to see a range for your own size and finish.
Our process, step by step
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
We visit your Bath home, measure up, talk through what you want and check the planning position.
Design and approvals
We produce the drawings and structural design, and manage the approvals so they are in place before work starts.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Common questions in Bath
How long does a side extension take to build in Bath?
On site, typically 10 to 18 weeks once approvals are in place. Before that, allow 6–14 weeks design and approvals.
Do I need building regulations approval in Bath?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Will my neighbours in Bath be involved?
If a planning application or prior approval is needed, the council notifies neighbours. If the work is on or near a shared boundary, party wall notices may also be needed.
Can I build over my driveway?
Yes, if the foundations work and you keep any parking the council requires. Drains and services under drives are common, so we check before design.
How much does a side extension cost?
Our guide range is about £1,780 to £3,470 per m² including VAT, depending on specification, so a standard 18 m² single-storey side extension lands around £37,500 to £49,000 in Bath.
Book a free site visit in Bath
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.