Do I need Planning Permission for and Extension?

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Permitted Development Guide

Do I Need Planning Permission for an Extension, Outbuilding, or Garden Room?

Often, the answer is no. Many home projects in England fall under Permitted Development (PD), allowing you to build without a full application if you stay within set limits. However, those limits are strict—and they only apply to householders, not flats or maisonettes.

Step 1: Check whether your rights exist

• • PD rules do not apply to flats, maisonettes, or houses created through certain change-of-use rights.
• • Planning conditions or Article 4 Directions can remove your rights. Always check your property's planning history.
• • Properties on designated land (Conservation Areas, National Parks, AONBs, World Heritage Sites) or listed buildings face much tighter restrictions.

Step 2: Extensions checklist

• ✓ Front Elevations: Nothing can extend forward of the main (usually front) elevation.
• ✓ Single-Storey Rear: Up to 4m beyond original rear wall for detached homes, or 3m for other houses. Max height 4m (eaves within 2m of boundary max 3m).
• ✓ Single-Storey Side: Max height 4m, and no wider than half the original house width.
• ✓ Two-Storey Rear: Max 3m extension, remaining at least 7m from the rear boundary.
• ✓ Original Limits: "Original house" means as built, or as it stood on 1 July 1948. Past extensions count against your allowance!
• ✓ Materials: Must match or be similar to existing house materials.
• ✓ Designated Land: All side extensions and multi-storey rear extensions require full planning permission.
• ✓ Larger Rear Extensions: Under Prior Approval (subject to neighbour consultation), limits increase to 8m (detached) or 6m (other houses) outside designated land.

Step 3: Outbuildings and garden rooms checklist

• ✓ Location: Must not be forward of the principal elevation.
• ✓ Heights: Single-storey only. Max eaves height 2.5m. Total height max 4m (dual-pitched) or 3m (other roofs). Max 2.5m overall height within 2m of boundary.
• ✓ Features: No verandas, balconies, or raised platforms higher than 0.3m.
• ✓ Coverage: Must cover no more than half the land surrounding the original house.
• ✓ Special Land / Heritage: 10 sq m max limit over 20m from house in National Parks/AONBs. Side outbuildings need permission in conservation areas. All outbuildings require permission for listed buildings.
• ✓ Intended Use: Covers incidental uses (home office, gym, studio). Does NOT cover self-contained living accommodation.

💡 Two things people often miss

1. Building Regulations are separate: Permitted development removes planning hurdles, but does NOT exempt you from building regulations approval.
2. Lawful Development Certificates (LDC): An LDC provides official, legally binding proof from the council that your build was lawful. It's optional, but saves huge stress when selling your home.

Not sure if your project qualifies?

We can check your property's planning history and PD rights before you spend a penny on architectural drawings.

Contact Kippen Ash Today

Please note: This article provides general guidance for properties in England only and does not constitute formal legal or planning advice for your specific property. While all information is accurate to the best of our knowledge at the time of publication, the planning system is a moving feast and policy updates occur frequently. Always verify the latest rules or seek professional advice before starting works.