What is a Rear Extension?

A rear extension involves extending the back of your property into the garden or yard area. It can be single-storey or double-storey, and it can come in various styles to match or contrast your existing home.

Types of Rear Extensions

1. Single-Storey Rear Extension

• Great for kitchen/diner expansions, open-plan living
• Most common and often under Permitted Development

2. Double-Storey Rear Extension

• Adds bedrooms, bathrooms upstairs + living space below
• More planning permission hurdles but more value added

3. Wraparound Extension (Rear + Side Return)

• Ideal for Victorian/Edwardian terraces with a side alley
• Creates a large L-shaped space with loads of natural light

Key Benefits

• Adds significant usable space
• Perfect for modern open-plan layouts
• Can increase property value by 10–25%+
• Allows you to stay in the area you love, instead of moving

Planning Permission

You might not need it if it falls under Permitted Development (PD):

Under PD, you can extend:

• Up to 3m (terraced/semi-detached) or 4m (detached)
• Must not cover more than 50% of your land
• Must not exceed 4m in height (for single-storey)

Larger Home Extension Scheme (prior approval):

• You can extend up to 6m (terraced/semi) or 8m (detached)
• But you need to go through a neighbour consultation process

Double-storey extensions always need planning permission.

Building Regulations

Always required:

• Structural integrity (especially foundations)
• Insulation and energy efficiency
• Electrical, plumbing (if kitchen/bathroom involved)
• Fire safety, ventilation

Estimated Cost (UK 2025)

Single-storey rear extension:

£35,000–£70,000 depending on size and spec

Double-storey:

£60,000–£120,000+

Wraparound extension:

£80,000–£140,000+

High-spec finishes, structural glazing, or kitchen refits will increase the total.

Popular Uses

• Kitchen/dining/living “family hub”
• Utility room + downstairs WC
• Office or guest bedroom
• Upstairs: extra bedroom or en suite