Extension plans · Dorchester, Dorset
House Extension Plansin Dorchester
Extension design pack
Fixed price. 2-3 layout options. 48-hour delivery.
Based in Poole since 2017 · Covering Dorchester and the wider Dorset area
Extension types
Whatever your extension, we design it.
Single-storey extension
Rear or side extensions to add a kitchen, dining room, or living space. The most popular option.
Two-storey extension
Double the space with bedrooms above and living space below. Requires planning permission in most cases.
Internal reconfiguration
Move walls, open up rooms, and redesign your existing layout without extending the building footprint.
Cost estimator
Rates for Dorchester
6m × 4m = 24m²
Estimated cost in Dorchester
Excl. VAT (£9821 – £14720)
Local insight: Dorchester build costs are mid-range for Dorset. Poundbury extensions must follow the Duchy of Cornwall design code, which specifies traditional materials and construction methods.
Want a professional layout?
Upload your floor plan — 2–3 options in 48hrs
First room £29.99 · Additional rooms £19.99
From £29.99 →How it works
Three steps to your extension plan.
Share your space
Paste a Rightmove link or upload photos with rough measurements. Takes 60 seconds.
Receive your options
We draw 2-3 professional floor plan options and share them through your online portal within 48 hours.
Decide with confidence
Love it? We handle scanning, planning applications, and builder coordination. No obligation.
House Extensions in Dorchester: County Town Design Expertise
Dorchester is Dorset's county town, combining a historic town centre with modern suburban expansion and the distinctive Poundbury development on its western edge. The housing stock ranges from Georgian townhouses on High West Street and South Street through to Victorian terraces in Fordington, post-war estates in Poundbury Gate, and the architecturally controlled homes of Poundbury itself. Each area requires a different design approach for extensions.
Poundbury: Unique Design Controls
Poundbury is Prince Charles's experimental urban extension to Dorchester, built according to traditional architectural principles. Homes here are subject to strict design codes that control materials, window proportions, roof forms, and external colours. Extensions must comply with the Poundbury Design Code and are assessed by both Dorset Council and the Duchy of Cornwall's architectural advisor. We understand these dual requirements and design extensions that pass both assessments, using the specified materials and proportions from the outset.
Georgian and Victorian Properties in the Town Centre
Dorchester's historic core features Georgian townhouses, Victorian terraces, and period cottages. Many are within the conservation area or are individually listed. Extensions focus on rear additions that do not alter the street-facing elevation, using sympathetic materials that complement the existing stone and brick. We produce designs that satisfy Dorset Council's conservation team and include heritage impact assessments where required.
Suburban Estates and Surrounding Villages
The residential estates of Charlton Down, Poundbury Gate, and the surrounding villages of Charminster, Maiden Newton, and Cerne Abbas offer a mix of modern and period housing on varied plot sizes. Standard Permitted Development rights generally apply outside the conservation area, making extensions straightforward. We design layouts that maximise your extension potential within PD limits, avoiding the cost and delay of a full planning application.
Typical properties in Dorchester
Chaseborough Square, Poundbury — neo-traditional residential architecture in Dorchester's model urban extension
Fig. 2
Middle Farm House, Poundbury — the original Victorian farmhouse predating the Poundbury development
Fig. 3
Planning Permission for Extensions in Dorchester
Dorchester falls under Dorset Council, which processes all Householder Planning Applications for the area. The town has a large conservation area covering the historic centre and surrounding streets, plus the unique Poundbury Design Code that applies to the western extension. Understanding which regime applies to your property is the first step in any extension project.
How does Dorset Council handle extension planning in Dorchester?
Dorset Council typically processes Householder Planning Applications within eight weeks at a fee of £258. For properties within the conservation area, PD rights are restricted and extensions usually need full planning permission. Outside the conservation area and Poundbury, standard PD rules apply. We check your property's designation and planning history before recommending a route, ensuring you only pay for the consents you actually need.
What are the Poundbury Design Code requirements for extensions?
Extensions to Poundbury properties must comply with the Poundbury Design Code, which specifies approved materials, window-to-wall ratios, roof pitches, and external finishes. Proposals are reviewed by the Duchy of Cornwall's architectural advisor in addition to Dorset Council's planning team. We design to the Code from the start, including the correct stone, render, and slate specifications in our drawings. This avoids the costly back-and-forth that occurs when designs do not meet the Duchy's expectations.
House Extension Options in Dorchester: Cost & Planning Comparison
| Extension Type | Typical Cost/m² | Planning Required? | Typical Duration |
|---|---|---|---|
| Single-storey rear | £1,700–£2,400 | Usually PD | 8–12 weeks |
| Two-storey rear | £1,500–£2,100 | Often PD | 12–16 weeks |
| Poundbury extension | £2,200–£3,000 | Planning + Design Code | 16–24 weeks |
| Conservation area ext. | £2,000–£2,800 | Planning required | 14–20 weeks |
Costs are indicative for Dorchester and vary by specification, site conditions, and builder. Our £250 design pack helps you compare options before committing.
Detailed plans you can build from.
Your extension design pack includes 2-3 professional floor plan options with accurate dimensions, room flow, and layout variations. Drawn by qualified drafters — not AI-generated renders.
- 2-3 layout options included
- Accurate room dimensions
- Share directly with builders
- Planning application ready
Transparent pricing
Every step is fixed-price.
Design Discovery
2-3 floor plan options from photos or Rightmove
3D Laser Scan
Millimetre-accurate measured survey of your home
Lawfulness Certificate
Permitted Development certificate application
Planning Application
Full Householder Planning Application submission
Common questions
Extension plans in Dorchester
Areas we cover
Extension plans across Dorset
Ready to start your extension in Dorchester?
Get 2-3 professional floor plan options for £250. No obligation, no follow-up calls.
Every plan drawn by qualified drafters · Covering Dorchester and the wider Dorset area