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.
We arrange a single-storey extension for homeowners in Gerrards Cross and the wider Buckinghamshire. The job is planned, priced and managed by us and carried out by tradespeople engaged under our contract, so there is one agreement and one contact. On a typical home the work takes 10–16 weeks on site, and guide pricing in the South East is £39,000–£84,000, VAT included.
- Guide price
- £39,000–£84,000 inc VAT
- Time on site
- 10–16 weeks on site
- Postcodes
- SL9
- Planning rules
- England
- Local area
- Buckinghamshire
- Survey
- Free, with a written quote
What should you budget for a single-storey extension in Gerrards Cross?
To help you plan, we show what a single-storey extension typically costs in Gerrards Cross instead of holding figures back for a sales call. The range is £39,000–£84,000 with VAT, using rates in the South East that are about 12% above the national guide. A free survey then fixes your actual price.
| Type of job | What it usually involves | Guide in Gerrards Cross |
|---|---|---|
| Small extension (8–12m²) | A modest rear or side extension, such as a utility room or a slightly larger kitchen. | £24,500–£45,000 |
| Typical rear extension (15–25m²) | A kitchen-diner or family room with bifold doors and a rooflight or lantern. | £39,000–£84,000 |
| Large or wrap-around (30m² plus) | A wrap-around or wide rear extension, often with structural steelwork into the house. | £78,000–£146,000 |
What moves the price up or down:
- 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
Scope of the work
- Groundworks, foundations and below-ground drainage
- Cavity walls built and insulated to building regulations
- Steel beams to open into the existing house
- Windows and external doors, including bifolds if chosen
- Plastering, screed floor and internal doors
- Building control inspections and completion certificate
Building in Gerrards Cross
Buckinghamshire runs from Chiltern villages of brick and flint, through Metroland interwar semis around Amersham and Chesham, to Victorian terraces in High Wycombe and Aylesbury. Milton Keynes adds estates built from the 1970s onwards in brick, render and timber frame, and new housing continues to spread around its edges.
Chiltern cottages may need lime repairs and careful window choices in conservation areas. Interwar semis suit hip-to-gable lofts and rear extensions, while Milton Keynes homes often need roofline renewal, replacement doors and garage conversions.
These patterns matter for a single-storey extension: older walls, roofs and floors in Gerrards Cross can need different materials or extra preparation compared with newer homes.
Planning and building rules in Gerrards Cross
The notes below cover England, which is where Gerrards Cross sits. Rules change and every property is different, so we speak to the council before pricing your job.
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?
Free site survey
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.
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.
Booking the work
With the quote agreed, we book the work in and handle preparation: permissions where needed, building control notifications, material orders and access arrangements for your Gerrards Cross property.
Build and hand over
The work is carried out to the agreed specification, with floors and furniture protected and the site kept tidy. At the end we clean up, walk through the finished job with you and hand over any certificates.
Why homeowners choose us
Single-storey extensions in Gerrards Cross: questions
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.
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.
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.
How much will a single-storey extension cost in Gerrards Cross?
As a guide, expect to pay £39,000–£84,000 including VAT for a single-storey extension in Gerrards Cross. That range is adjusted for the South East, which runs about 12% above the national guide. Where your project lands depends on size, materials, access and the condition of what is already there. We confirm a fixed price in writing after a free survey of your home.
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.
Also covering areas around Gerrards Cross
Gerrards Cross and its SL9 postcodes are part of our coverage. Homeowners in Chalfont Saint Peter, Uxbridge and Rickmansworth can also book a free survey with us and receive a written price for their job.