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Rear House Extension Ideas UK: Inspiration, Costs and Planning Guide

A rear house extension is the single most popular home improvement in the UK. By extending into the garden, you can create the open-plan kitchen-diner, family living space, or home office your current home lacks.

The Best Rear Extension Ideas

1. Open-Plan Kitchen, Dining and Living Space

The most popular use. Remove the wall between kitchen and dining room, extend at the rear. Key features: full-width bi-fold or sliding doors, roof lantern, kitchen island, underfloor heating.

2. Family Room

A dedicated family room — for children to play, watch TV, or do homework without taking over the living room. Often glazed partition from kitchen for acoustic separation.

3. Home Office

A dedicated home office with separate garden access is one of the most valued features for buyers. Key features: natural light, acoustic separation, built-in networking infrastructure.

4. Orangery

More glazing than a conventional extension, creating a light-filled garden room feel. Traditional orangeries have solid perimeter with glazed lantern; modern versions blur the line.

5. Garden Gym

Increasingly popular since 2020. Needs rubber flooring, ventilation, height for equipment, and ideally a shower room.

Costs UK 2024

• Small rear extension (under 15m²): £22,000 – £38,000
• Medium (15–25m²): £38,000 – £60,000
• Large (25–40m²): £60,000 – £90,000

Design Principles

Garden Connection

Full-width openings (bi-fold, sliding, or pivot doors) and level thresholds create seamless flow between inside and out.

Natural Light

South-facing gardens get sun; north-facing need a roof lantern. For south-facing, consider external blinds to prevent overheating.

Materials

Popular options: matching brick, render, timber cladding, zinc, or Corten steel for a contemporary look.

Planning Permission

Single-storey rear extensions up to 4m (detached) or 3m (other) qualify for permitted development. Up to 8m/6m under the Neighbour Consultation Scheme.

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Frequently Asked Questions

Kitchen Extension Costs UK 2024: Everything You Need to Budget For

A kitchen extension is the most popular home improvement in the UK. The dream of an open-plan kitchen, dining and living space with bi-fold doors to the garden is within reach for most homeowners.

Average Costs UK 2024

• Small kitchen extension (under 15m²): £25,000 – £45,000
• Medium (15–25m²): £45,000 – £70,000
• Large (25–40m²): £70,000 – £110,000
• Premium high-spec: £110,000 – £180,000+

In London, add 20–30%. These costs include architectural design, building regulations, and construction — but not the kitchen itself.

Detailed Cost Breakdown

Design and Planning

• Architectural drawings and planning: £2,500 – £6,000
• Structural engineering: £750 – £2,000
• Building regulations: £800 – £1,500
• Party wall surveyor (if required): £1,000 – £3,000

Construction

• Foundations and groundworks: £5,000 – £15,000
• Walls and roof structure: £10,000 – £25,000
• Bi-fold or sliding doors: £4,000 – £14,000
• Roof lantern or skylight: £3,000 – £10,000
• Underfloor heating: £2,500 – £6,000
• Electrical work: £2,500 – £6,000
• Plumbing: £2,000 – £5,000
• Plastering and decoration: £2,000 – £5,000
• Flooring: £2,000 – £6,000

Kitchen Costs (Separate)

• Flat-pack kitchen (IKEA etc.): £3,000 – £8,000
• Mid-range fitted kitchen: £8,000 – £20,000
• Premium German kitchen: £20,000 – £60,000+

Key Cost Drivers

Bi-Fold Doors

Aluminium bi-folds start at ~£1,500 per linear metre installed. A 4m opening typically costs £6,000–£10,000 for quality units.

Roof Lantern

£3,500–£12,000 depending on size. Custom-made lanterns cost more; stock sizes are cheaper.

Underfloor Heating

Electric: £500–£1,500 to install (cheaper to install, more expensive to run). Wet/water-based: £2,500–£5,000 to install but cheaper to run long-term.

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Frequently Asked Questions

Wrap-Around Extensions: The Complete UK Guide for 2024

A wrap-around extension combines a rear extension with a side return extension to create an L-shaped addition that dramatically increases ground floor footprint — often by 20–40%.

What Is a Wrap-Around Extension?

It combines:

• Rear extension: Extends the back of the house into the garden
• Side return extension: Fills in the narrow alleyway beside Victorian and Edwardian terraces

The result is an L-shaped space that typically becomes a dramatic open-plan kitchen, dining, and living area.

Costs UK 2024

• Small wrap-around (under 30m²): £50,000 – £70,000
• Medium wrap-around (30–45m²): £70,000 – £100,000
• Large wrap-around (over 45m²): £100,000 – £140,000+

In London, costs are at the higher end due to labour costs and complexity.

Do You Need Planning Permission?

Rear Extension Component

A single-storey rear extension of up to 4m (detached) or 3m (other houses) can typically proceed under permitted development.

Side Return Component

Side extensions are more restricted. For terraced and semi-detached houses, side extensions usually require planning permission.

In practice: Most wrap-around extensions require a planning application for at least the side return component.

Design Tips

Maximise Natural Light

The junction between rear and side elements can create dark corners. Roof lanterns and large skylights are the solution.

Create Seamless Flow

The best wrap-arounds create a single flowing space. Plan carefully where kitchen, dining, and living areas sit in the L-shaped footprint.

Connection to Garden

Full-width bi-fold or sliding doors across the rear elevation are almost universal in modern London wrap-around extensions.

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Frequently Asked Questions