A single-storey extension is a new ground-floor room built onto your house, usually at the rear or side, with its own foundations, walls and roof, creating a bigger kitchen, living space or bedroom without moving home.
Bath sits within our coverage for a single-storey extension, as do neighbouring Keynsham, Trowbridge and Kingswood. Before giving a price we want to see the property: the condition of what's there now, the access, and anything that might need extra work. The guide range for the South West is £35,500–£76,000 including VAT, and your written quote will spell out exactly what that covers.
- Guide price
- £35,500–£76,000 inc VAT
- Time on site
- 10–16 weeks on site
- Postcodes
- BA1 and BA2
- Planning rules
- England
- Local area
- Bath and North East Somerset
- Survey
- Free, with a written quote
What should you budget for a single-storey extension in Bath?
To help you plan, we show what a single-storey extension typically costs in Bath instead of holding figures back for a sales call. The range is £35,500–£76,000 with VAT, using rates in the South West that are about 2% above the national guide. A free survey then fixes your actual price.
| Type of job | What it usually involves | Guide in Bath |
|---|---|---|
| Small extension (8–12m²) | A modest rear or side extension, such as a utility room or a slightly larger kitchen. | £22,500–£41,000 |
| Typical rear extension (15–25m²) | A kitchen-diner or family room with bifold doors and a rooflight or lantern. | £35,500–£76,000 |
| Large or wrap-around (30m² plus) | A wrap-around or wide rear extension, often with structural steelwork into the house. | £71,000–£133,000 |
What moves the price up or down:
- Floor area, shape and number of corners
- Roof type, rooflights, lanterns and the amount of glazing
- Steelwork needed to open into the existing house
- Finishes, kitchen, flooring and heating specification
What’s included?
- Flat or pitched roof, with rooflights or a lantern if specified
- Steel beams to open into the existing house
- Electrics and plumbing by qualified trades, with certificates
- Windows and external doors, including bifolds if chosen
- Plastering, screed floor and internal doors
- Building control inspections and completion certificate
What are homes like around Bath?
Somerset's building stone varies widely: Bath stone in Bath, golden Ham stone around Yeovil, blue lias in villages on the Levels and Mendip stone in the north. Weston-super-Mare has Victorian villas and terraces, Taunton and Bridgwater have brick terraces and post-war estates, and new housing continues to spread around the larger towns.
Stone properties often need lime pointing, stone repairs and windows that respect conservation areas, especially in Bath. Brick terraces suit loft rooms and extensions, and estate homes commonly take garage conversions.
These patterns matter for a single-storey extension: older walls, roofs and floors in Bath can need different materials or extra preparation compared with newer homes.
Do you need permission in Bath?
Homes in Bath come under the regulations for England, summarised below. We don't rely on general rules alone: we confirm the position for your address with the council before a quote goes out.
In England, many single-storey rear extensions are permitted development: typically up to 3 m deep on a semi-detached or terraced house and 4 m on a detached house, no more than 4 m high, and covering no more than half the land around the original house. Larger rear extensions can go through the prior approval process. Side extensions, flats, listed buildings, conservation areas and homes where permitted development rights have been removed need planning permission.
Building Regulations approval is needed for almost every extension, covering foundations, structure, insulation, drainage, ventilation and fire safety. If the work is on or near a shared wall or boundary, the Party Wall etc. Act 1996 may apply.
Rules change and every property is different, so we check the planning history and constraints for your address before we quote.
What happens after you get in touch?
A visit to your home
It starts with a survey at the property, free of charge. We check condition, access and services, ask how you want the finished result to look, and answer any questions you have about a single-storey extension.
Your fixed price
The quote arrives in writing, not over the phone. It covers the full scope, the finishes you've chosen, any exclusions and the payment schedule, with a fixed price tied to that specification.
Dates and permissions
Once you accept, we agree start dates, order materials and deal with any planning, building control or neighbour notices the job needs. You'll know who is coming and when before work begins.
On site to finish
On site, the agreed plan is followed and any change is put in writing first. At completion we do a final clean, go through the snagging list with you and leave you with the relevant documents.
How we work
Questions about a single-storey extension in Bath
Do I need planning permission in Bath?
It depends on the work, the size of the project, your property type and whether the building is listed or in a conservation area. Bath is in England, so England's rules apply. Many smaller jobs need no planning application, but some still need building control approval. We check what applies to your address before quoting.
Do I need planning permission for a single-storey extension?
Whether you need planning permission depends on the extension's size and height, how close it is to boundaries, your home's location, whether it is listed or in a conservation area, and which UK nation you live in. In England, many rear extensions up to 3m deep on a semi or terrace, or 4m on a detached house, can be built under permitted development. We check the rules that apply to your home before quoting.
What happens at the survey?
We visit your home at a time that suits you, look at the area involved, take measurements and check access, condition and any services that might be affected. We talk through what you want from a single-storey extension, explain the options and answer questions. There is no charge and no obligation; afterwards we send a written quote.
Do I need an architect for an extension?
You need proper drawings for an extension, but not always a full architect service. A designer or architectural technician can produce planning and building regulations drawings, and a structural engineer provides beam and foundation calculations. If you already have drawings, we price from them. If not, we can arrange the drawings and calculations as part of the project so everything is coordinated from the start.
Can we stay at home during the build?
Most people stay at home while we build a single-storey extension, because the new structure goes up outside before we break through. The disruptive part is usually the last few weeks, when we open into the house and fit the kitchen. We put up dust screens, keep a safe route through the house and agree a temporary kitchen setup if needed. Water and power are only off for short, planned periods.
Near Bath
We cover every part of Bath, including BA1 and BA2, and nearby Keynsham, Trowbridge and Kingswood. Wherever you are within that patch, the survey is free and the quote comes to you in writing.