Thinking About a House Extension? Here’s What You Need to Know

One of the most confusing parts of extending your home is understanding whether you need planning permission or if your project qualifies as permitted development. Getting this wrong can lead to delays, extra costs, or even the need to undo work—something no homeowner wants!

As an Architectural Technologist based in Bournemouth, I help homeowners navigate this process, making it simple and stress-free. In this guide, I’ll explain the key differences and what you need to know before starting your extension.

What’s the Difference Between Planning Permission & Permitted Development?

✅ Planning Permission

• A formal application submitted to the local council for approval.
• Required for major changes that impact the local environment.
• Typically takes 8 weeks for a decision.
• Costs between £250 – £500 in fees.

✅ Permitted Development (PD)

• Allows certain extensions without needing full planning permission.
• Subject to strict rules on size, height, and appearance.
• Must still comply with building regulations.
• Typically faster and cheaper than applying for full permission.

🔹 Even if your extension falls under Permitted Development, you can apply for a Lawful Development Certificate (LDC) to confirm compliance. This provides official proof from the council that your project meets all requirements, which can be useful when selling your home or avoiding future disputes.

Do You Need Planning Permission for a House Extension in Bournemouth?

In many cases, you won’t need planning permission if your extension meets permitted development rules. Here are the key limits to watch out for:

🔹 Single-Storey Extensions (PD Rules)

• Must not extend more than 3m from the rear of a terraced/semi-detached house.
• Must not extend more than 4m from a detached house.
• Maximum height: 4m (or 3m if within 2m of a boundary).

🔹 Double-Storey Extensions (PD Rules)

• Cannot extend more than 3m from the original house.
• Must be at least 7m from the rear boundary.
• Roof ridge cannot be higher than the existing house.

🔹 Side Extensions (PD Rules)

• Maximum width: Half the width of the original house.
• Maximum height: 4m.

🔹 Loft Conversions (PD Rules)

• Can add up to 40m³ for terraced houses or 50m³ for detached/semi-detached houses.
• No extensions beyond the existing roof slope facing the road.
• No balconies, raised platforms, or dormers higher than the original roof.

🚨 When You MUST Apply for Planning Permission:

• If your home is in a conservation area or listed.
• If you want to extend beyond PD limits.
• If your plans significantly alter the appearance of the property.

🔹 Bournemouth-Specific Considerations:

• Certain areas near the coast have restricted development rules to protect views.
• Flood zones may require additional permissions.
• Conservation areas like West Cliff, Talbot Woods, and East Cliff have stricter guidelines.

Applying for a Lawful Development Certificate (LDC) in Bournemouth

Even if your extension falls under permitted development, it’s a good idea to apply for a Lawful Development Certificate (LDC).

Why Get an LDC?

✔ Official proof that your extension meets legal requirements.
✔ Prevents issues when selling your home—buyers may request proof of compliance.
✔ Avoids future disputes—councils or neighbours cannot challenge the legality of your extension later.

How to Apply for an LDC:

1️⃣ Submit an application to BCP Council via the Planning Portal.
2️⃣ Provide detailed drawings and plans of the extension.
3️⃣ Council reviews your application (typically within 8 weeks).
4️⃣ Approval granted—you receive an official certificate.

📌 Cost: Around £100 – £200, but this varies depending on the council.

How to Apply for Planning Permission in Bournemouth

If your extension doesn’t meet permitted development rules, you’ll need to submit a planning application to BCP Council (Bournemouth, Christchurch & Poole).

Here’s the process:
1️⃣ Pre-Application Advice – Optional, but helpful to avoid rejections.
2️⃣ Submit an Application – Through the Planning Portal (cost: £250 – £500).
3️⃣ Public Consultation – Neighbours may be informed of your plans.
4️⃣ Decision (Usually 8 Weeks) – The council approves, rejects, or requests modifications.
5️⃣ Approval Granted – Work must begin within 3 years.

📌 Top Tip: A well-prepared application is more likely to be approved. I can help ensure your plans meet all the necessary requirements.

What Happens If You Build Without Permission?

❌ If your extension needs planning permission but doesn’t have it, the council can issue a retrospective application or force you to undo the work.

✅ Lawful Development Certificates (LDCs) – If you’re unsure whether your project is permitted development, you can apply for an LDC to confirm compliance.

Final Thoughts: What’s the Best Option for Your Home?

• If your extension qualifies as permitted development, you can save time and money by avoiding the full planning process.
• If you need planning permission, it’s important to get it right the first time to avoid delays and extra costs.
• Even for Permitted Development projects, an LDC is a great way to provide official proof that your extension meets regulations.

📞 Need help navigating planning rules?
I specialise in simplifying the planning and building regulations process for Bournemouth homeowners.

🔹 Get in touch today for expert advice on your house extension!