How to Build a Permitted Development Rear Extension

Expanding your home with a rear extension is a great way to add space and increase property value. But before you start, it’s essential to check whether your project qualifies under permitted development rights. A permitted development rear extension allows homeowners to extend their property without the need for full planning permission, saving time and hassle.

If you’re considering an extension, a modular rear extension offers the most efficient, cost-effective, and convenient solution.

What is a Permitted Development Rear Extension?

A permitted development rear extension refers to a home extension that falls within the limits set by the UK’s Permitted Development (PD) Rights, meaning it doesn’t require full planning permission. However, your extension must comply with specific criteria set by your local authority. You can also find out more here.

Key Benefits of a Permitted Development Rear Extension

• No Planning Permission Required – As long as you meet the PD guidelines
• Faster Approval Process – Avoid long waits for planning applications
• Cost-Effective – Save money on planning fees
• Minimal Disruption – Modular options offer quicker installation
• Increases Home Value – Adds functional space and boosts property appeal

Permitted Development Rear Extension Rules

To qualify under permitted development, your rear extension must adhere to the following:

• Single-storey only
• Must not exceed 3m in depth for terraced and semi-detached houses
• Must not exceed 4m in depth for detached houses
• Maximum height of 4m (or 3m if within 2m of a boundary)
• No more than 50% of the original land around the house can be built upon
• Must not extend beyond the rear wall of the original house by more than 6m (semi-detached) or 8m (detached) under the larger home extension scheme (subject to prior approval)

Before proceeding, always check with your local planning authority to ensure compliance.

The Best Alternative: Modular Rear Extensions

A modular extension is a pre-fabricated home addition built off-site and assembled on location in a fraction of the time compared to traditional builds.

Why Choose a Modular Extension?

• Faster Construction – Installed in weeks, not months
• Cost-Effective – Fixed pricing avoids unexpected costs
• Minimal On-Site Disruption – Perfect for busy homeowners
• Highly Customisable – Tailored to your space and style
• Eco-Friendly – Better insulation and reduced waste

Step-by-Step Guide to Building a Permitted Development Rear Extension

Step 1: Check Your Eligibility

Review the PD guidelines and consult your local council’s planning portal. If in doubt, apply for a Lawful Development Certificate (LDC) for confirmation.

Step 2: Choose Between Traditional or Modular

A traditional extension takes months, whereas a modular extension is built off-site and installed in a matter of weeks.

Step 3: Design Your Extension

Work with a specialist modular builder to design a rear extension that meets your needs. Consider:

• Size & layout
• Material finishes
• Windows & doors
• Roof options (flat or pitched)

Step 4: Obtain Necessary Approvals

• Permitted Development Notification (if applicable)
• Building Regulations Approval (for safety compliance)

Step 5: Prepare the Site

For modular extensions, groundwork is minimal. The foundations are prepared in advance, meaning installation is quick and efficient.

Step 6: Installation & Finishing Touches

Once the modular sections are delivered, installation can take just 1-2 weeks, with minimal disruption.

Costs of a Permitted Development Rear Extension

The cost depends on factors such as size, materials, and location. Here’s an estimate:

Extension Type	Traditional Build Cost	Modular Extension Cost
3m Rear Extension	£30,000 – £45,000	£20,000 – £35,000
4m Rear Extension	£40,000 – £55,000	£25,000 – £40,000
6m Rear Extension	£55,000 – £75,000	£35,000 – £50,000

For an accurate cost estimate, use our House Extension Cost Calculator.

FAQs About A Permitted Development Rear Extension

1. Do I need planning permission for a rear extension?

If your extension meets Permitted Development guidelines, planning permission is not required.

2. What size extension can I build under Permitted Development?

You can extend up to 3m for terraced/semi-detached houses and 4m for detached homes without prior approval.

3. Are modular extensions cheaper than traditional builds?

Yes! Modular extensions are typically 20-30% cheaper due to reduced labour and material costs.

4. How long does a modular rear extension take?

A traditional build takes 4-6 months, while a modular extension can be installed in 4-6 weeks.

5. Can I live in my house during the extension build?

Yes! Modular extensions cause minimal disruption and don’t require you to move out.

6. Are modular rear extensions energy-efficient?

Yes! Superior insulation and eco-friendly materials make them highly energy-efficient.

7. How do I know if my extension qualifies for Permitted Development?

Check with your local planning authority or apply for a Lawful Development Certificate (LDC).

8. Can I customise a modular rear extension?

Yes! Modular extensions are tailored to match your home’s style and needs.

9. Will a rear extension add value to my home?

A well-built extension can increase your home’s value by 10-20%.

10. How do I get started?

Contact Vergolus for a consultation and request an information pack today!

A Permitted Development Rear Extension

A permitted development rear extension is a fantastic way to expand your home without the hassle of planning permission. By choosing a modular extension, you benefit from faster construction, lower costs, and minimal disruption.

If you’re considering an extension, check your local authority’s regulations and explore modular options for a stress-free build. Contact Vergolus today for a consultation or request an information pack to get started!