Extension plans and drawings in Wiltshire
We prepare extension plans and drawings for homes across Wiltshire, on their own or as the first stage of a full design and build project.
- Guide priceFrom £1,200 inc VAT
- PlanningWe find the right route for you
- Towns covered8
- Site visitFree, no obligation
Towns in Wiltshire
Design and approval fees for Wiltshire
These are guide fees for Wiltshire, adjusted for South West England (×1.02) and including VAT. Council application and inspection fees are paid separately.
| Option | What it covers | Guide price |
|---|---|---|
| Essential | Measured survey and planning drawings | £1,200 – £2,250 |
| Standard | Planning drawings plus building regulations drawings | £2,200 – £3,900 |
| Premium | Full pack with structural calculations and 3D visuals | £3,450 – £5,650 |
Try the guide-price tool to see a range for your own size and finish.
Do I need planning permission in Wiltshire?
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 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.
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 is included
- Building regulations drawings and specification
- Planning drawings: existing and proposed plans and elevations, site and location plans
- Measured survey of the house and garden
- Two or three layout options to compare
- Structural calculations from an engineer (full pack)
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.
Local to Wiltshire
Towns we cover in Wiltshire include Swindon, Salisbury, Trowbridge, Chippenham, Melksham, Devizes, Warminster, Calne. South West homes range from terraced streets in the cities to stone cottages and bungalows in the countryside, and conservation areas are common in historic centres.
How the project works
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
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Common questions in Wiltshire
Do you cover all of Wiltshire?
Yes, across the whole of Wiltshire. Site visits are free and there is no obligation.
Do I need building regulations approval in Wiltshire?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Wiltshire, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
How much do extension plans cost?
Our design packs range from about £1,200 to £5,650 including VAT, from planning drawings only to a full pack with building regulations drawings, structural calculations and 3D views. Council fees are separate.
Can I use your drawings with another builder?
Yes. Once paid for, the drawings are yours to use for your project.
Book a free site visit in Wiltshire
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.