Extension plans and drawings across Buckinghamshire
We prepare extension plans and drawings for homes across Buckinghamshire, on their own or as the first stage of a full design and build project.
- Guide priceFrom £1,300 inc VAT
- PlanningWe find the right route for you
- Towns covered9
- Site visitFree, no obligation
Towns in Buckinghamshire
Who this service is for
- Anyone who wants fixed designs before getting build prices
- Homeowners at the very start of a project
- Projects that need a planning application or other approval
The most expensive changes are the ones made after the steel is ordered. A good design stage settles layout, heights, glazing and services on paper, so the build price is firm.
Extensions in and around Buckinghamshire
Towns we cover in Buckinghamshire include Milton Keynes, High Wycombe, Aylesbury, Bletchley, Amersham, Chesham, Gerrards Cross, Chalfont St Peter. Homes across the South East range from Victorian terraces in the older town centres to large detached houses on the edges, so the right extension type varies street by street.
Do I need planning permission in Buckinghamshire?
In England the main routes are permitted development (ideally confirmed with a lawful development certificate, £274), larger home extension prior approval (£249, 42 days) and a householder planning application (£548, normally 8 weeks), with council fees as set from 1 April 2026.
Homes in conservation areas, national parks, National Landscapes (formerly AONBs), the Broads and World Heritage Sites have tighter rules, so we always check the property's status and planning history before design starts.
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.
Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
Applications are decided by the local planning authority (your district, borough or unitary council).
What it costs in Buckinghamshire
These are guide fees for Buckinghamshire, adjusted for South East England (×1.12) and including VAT. Council application and inspection fees are paid separately.
| Option | What it covers | Guide price |
|---|---|---|
| Essential | Measured survey and planning drawings | £1,300 – £2,500 |
| Standard | Planning drawings plus building regulations drawings | £2,450 – £4,300 |
| Premium | Full pack with structural calculations and 3D visuals | £3,800 – £6,200 |
Try the guide-price tool to see a range for your own size and finish.
What happens next
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
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
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 Buckinghamshire
Will my neighbours in Buckinghamshire 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.
Who do I contract with in Buckinghamshire?
Your contract is with S&K Property Investments and Improvement Ltd, which designs and manages the project and the build teams who carry it out.
Do you cover all of Buckinghamshire?
Yes, across the whole of Buckinghamshire. Site visits are free and there is no obligation.
How much do extension plans cost?
Our design packs range from about £1,300 to £6,200 including VAT, from planning drawings only to a full pack with building regulations drawings, structural calculations and 3D views. Council fees are separate.
Do I need an architect?
Not necessarily. For most extensions an experienced designer or architectural technologist is enough. For listed buildings or complex sites an architect’s input can help.
Book a free site visit in Buckinghamshire
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.