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.
Uxbridge sits within our coverage for a single-storey extension, as do neighbouring Ruislip, Hayes and Gerrards Cross. 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 London is £45,500–£98,000 including VAT, and your written quote will spell out exactly what that covers.
- Guide price
- £45,500–£98,000 inc VAT
- Time on site
- 10–16 weeks on site
- Postcodes
- SL0, UB8, UB9, UB10 and UB11
- Planning rules
- England
- Local area
- Greater London
- Survey
- Free, with a written quote
Single-storey extensions prices in Uxbridge
Below is a breakdown of typical costs for a single-storey extension in Uxbridge. Because rates in London are about 30% above the national guide, the overall guide comes to £45,500–£98,000, including VAT. Size, materials and access move the figure, and a free-of-charge survey settles it.
| Type of job | What it usually involves | Guide in Uxbridge |
|---|---|---|
| Small extension (8–12m²) | A modest rear or side extension, such as a utility room or a slightly larger kitchen. | £28,500–£52,000 |
| Typical rear extension (15–25m²) | A kitchen-diner or family room with bifold doors and a rooflight or lantern. | £45,500–£98,000 |
| Large or wrap-around (30m² plus) | A wrap-around or wide rear extension, often with structural steelwork into the house. | £91,000–£169,000 |
Your price depends mostly on:
- Floor area, shape and number of corners
- Roof type, rooflights, lanterns and the amount of glazing
- Ground conditions, foundation depth and drains to divert
- Finishes, kitchen, flooring and heating specification
What do you get?
- Groundworks, foundations and below-ground drainage
- 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
What are homes like around Uxbridge?
London's housing is dominated by Victorian and Edwardian terraces, often in yellow London stock brick, with Georgian terraces in central districts and mansion blocks across many inner areas. Outer boroughs have large belts of interwar semis, and there are extensive post-war council estates. Many houses have been split into flats, and conservation areas are widespread.
London Clay shrinks and swells with the seasons, and street trees close to houses can contribute to movement, which affects foundation design.
Whatever era your Uxbridge home dates from, we plan a single-storey extension around how it is actually built rather than a one-size-fits-all specification.
Planning and building rules in Uxbridge
Homes in Uxbridge 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.
The four stages
Free site survey
We arrange a free site survey on a date convenient to you. We measure up, look at the existing structure and access, and discuss your plans for a single-storey extension so the price reflects your home.
Written quote
After the survey we send a quote for a single-storey extension that fixes the price for the scope we've agreed. If you want to change materials or scope, we revise it in writing before anything is booked.
Getting ready
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.
Finish and handover
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.
Why homeowners choose us
Common questions
Is a flat roof or a pitched roof better on an extension?
A flat roof is quicker to build and usually costs less, gives a clean modern look and works well with a roof lantern. A pitched roof matches the main house, sheds water faster and allows a vaulted ceiling, but it costs more and its height can affect neighbours. Modern flat roofs in EPDM rubber or GRP last well when properly detailed. Planning rules on height can also decide the choice.
Which postcodes in Uxbridge do you cover?
We cover SL0, UB8, UB9 and UB10, along with the rest of London. If your postcode is not listed, get in touch anyway: our coverage is UK-wide, and we can usually arrange a survey wherever you live. Enter your postcode in the guide-price tool or contact form and we will confirm.
Who do I deal with during the job?
One point of contact manages your project from survey to handover. They schedule the trades working under our contract, keep you updated on progress, and are the person to call with any question. You don't need to coordinate builders, electricians or decorators separately, because that is part of what we do.
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 does a typical extension build look like week by week?
A typical single-storey extension follows the same order: clearing the site and digging foundations, building walls up to roof level, then fitting the roof and windows to make it weathertight. Electrics, plumbing, insulation and plastering follow. The last stage is opening into the house, laying the screed and fitting doors and finishes. Building control inspects at key stages, and we book those visits for you.
Near Uxbridge
Coverage for Uxbridge spans SL0, UB8, UB9 and UB10. Close by, Ruislip, Hayes and Gerrards Cross are covered too, and the rest of our UK-wide area follows the same survey-then-quote process from start to finish.