Conservation Area Extensions in Kent: What You Need to Know
10/11/2026
Planning a Kitchen Extension in Tonbridge: Layout, Light and Budget
10/11/2026
Permitted Development in a Conservation Area: Can You Extend Your House?
Being in a conservation area does not mean every alteration requires a full planning application. However, the extra restrictions make it particularly easy to apply a rule that does not fit your property. Before commissioning detailed extension drawings, establish whether permitted development is available, whether the design complies, and what evidence will confirm your position.
1. What is permitted development?
Permitted development is a national grant of planning permission for specified work, subject to conditions and limitations. It is not an exemption from all approvals. The question is more precise than 'is my extension small enough?'—the type of property, its planning history and the exact proposal all matter.
2. Which extension types need closer attention?
For houses in conservation areas, single-storey rear extensions may qualify under Class A (subject to limits). Extensions beyond a side wall of the original house are NOT permitted development on Article 2(3) land. Rear extensions of more than one storey are excluded, and larger-home prior approval is unavailable.
3. Is a three-metre rear extension automatically allowed?
No. Standard depth limits (3m attached, 4m detached) are measured from the relevant rear wall of the original house. Other tests include maximum height, eaves near boundaries, matching materials and covering less than 50% of the curtilage. Flats, maisonettes and converted houses are excluded.
4. Why do previous extensions matter?
The 'original house' is the house as first built, or as it stood on 1 July 1948. It is not necessarily the house you bought. Previous additions and cumulative enlargement affect whether a new proposal qualifies. Measuring only the extra piece does not answer the planning question.
5. What does an Article 4 direction change?
An Article 4 direction removes specified permitted development rights in a defined area. It does not mean development is prohibited, but requires a planning application for work otherwise permitted. Verify the direction's boundary, wording and covered works directly with the local authority.
6. Should you obtain a lawful development certificate?
A Lawful Development Certificate (LDC) formally proves that the proposed scheme is lawful under planning law. The council assesses legal criteria rather than design taste. An LDC provides vital legal certainty for future buyers and remortgages, though Building Regulations approval is still required.
7. What if the extension does not qualify?
Consider a planning application as part of the creative design process. The permitted development boundary is rarely the best boundary for your brief. Forcing a kitchen into an awkward footprint leaves circulation compromised. Compare alternatives with an architect before deciding.
8. Get your property checked before fixing the design.
Send TP Evans Architects your address, previous extension plans and a few photographs alongside an outline of the space you need. Checking the property's designations and history before detailing avoids aborted drawings, wasted fees and planning enforcement issues.
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Certainty before you build
Building under permitted development without formal verification carries real financial and legal risk—especially when selling your home. A Lawful Development Certificate or early architectural review ensures your investment is legally watertight.
Want your property checked?
TP Evans Architects reviews property history, local council designations and permitted development allowances across Tonbridge, Sevenoaks and Kent. Contact us to discuss your property.
Planning a project in Tonbridge or the surrounding villages?
TP Evans Architects is a Tonbridge practice working across Kent. We help homeowners establish whether permitted development applies, obtain Lawful Development Certificates, or prepare complete planning applications with photorealistic 3D visuals.
