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.

• Our kitchen extension service
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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

House Extension Ideas for UK Homes: The Complete 2024 Guide

Extending your home is one of the most rewarding investments you can make. A well-designed extension can transform daily life and add significant value — often far less disruptive and costly than moving house.

The Most Popular Extension Types

1. Rear Extension

The most common type in the UK. A rear extension adds space at the back, typically extending the kitchen, living room, or both. Single-storey rear extensions often qualify for permitted development.

Typical cost: £25,000 – £60,000

2. Side Return Extension

Fills in the narrow alleyway beside many Victorian and Edwardian terraces. Popular for widening kitchen spaces. Often combined with a rear extension as an L-shape.

Typical cost: £35,000 – £55,000

3. Wrap-Around Extension

Combines rear and side return extensions into one large L-shaped space — one of the most transformative types. See our extensions page for details.

Typical cost: £55,000 – £90,000

4. Double Storey Extension

Adds space on two floors for excellent value — twice the space for much less than twice the cost. Typically adds a bedroom and bathroom upstairs with extended living space below.

Typical cost: £60,000 – £120,000

5. Kitchen Extension

Consistently the most popular type in London. A kitchen extension creates an open-plan kitchen/dining/living space. Bi-fold doors to the garden are almost universal.

Typical cost: £40,000 – £80,000

Extension Ideas by Room Type

Open-Plan Kitchen/Dining/Living

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

Home Office

Post-pandemic, a dedicated home office has become one of the most sought-after features. An extension purpose-built as a home office — with good natural light, acoustic separation, and separate access — adds both lifestyle and market value.

Master Suite

A double storey extension adding bedroom and ensuite is one of the highest-value extensions. In London, moving from 3-bed to 4-bed can add £100,000+ to market value.

Design Principles

Natural Light

For north-facing extensions, roof lights or lanterns are essential. Bi-fold doors bring in light but also heat loss — balance with good insulation and underfloor heating.

Connection to Garden

The best extensions create a seamless indoor-outdoor connection through large glass doors.

Extensions Across London

• Battersea
• Richmond
• Greenwich
• Lewisham

Frequently Asked Questions

Single Storey Extension Costs UK 2024

A single storey extension is the most popular way to add space to a UK home. Whether extending your kitchen, creating open-plan living space, or adding a home office, it can transform how your home works.

Average Costs UK (2024)

• Small extension (under 15m²): £20,000 – £35,000
• Medium extension (15–25m²): £35,000 – £55,000
• Large extension (25–40m²): £55,000 – £85,000
• Premium/high-spec: £85,000 – £150,000+

In London, add 20–30%. Our single storey extension service covers all London boroughs.

Cost Drivers

Size and Footprint

Larger extensions offer better value per square metre due to shared fixed costs (foundations, roofing, connection to house).

Specification and Finishes

Internal finishes make a huge difference. Bi-fold doors, underfloor heating, and bespoke kitchen add significant cost.

Roof Type

Flat roofs are cheaper than pitched. A roof lantern adds £5,000–£15,000 but dramatically improves natural light.

Structural Complexity

Load-bearing wall removal and steel beams add cost. A structural engineer survey (£500–£1,500) identifies requirements early.

Detailed Breakdown (Typical 20m², London)

• Architectural design: £2,500 – £6,000
• Structural engineering: £750 – £2,000
• Planning application (if required): £1,500 – £3,500
• Building regulations: £800 – £1,500
• Foundations and groundworks: £5,000 – £12,000
• Structure (walls, roof): £12,000 – £22,000
• Windows and doors (incl. bi-folds): £4,000 – £12,000
• Electrical work: £2,000 – £5,000
• Plumbing: £2,000 – £6,000
• Plastering and decoration: £2,000 – £4,000
• Flooring: £1,500 – £5,000

Does It Add Value?

A well-designed single storey extension typically adds 5–15% to your property value. In London, the return can be higher when the extension creates a genuinely improved open-plan living space.

Extensions Across London

• Battersea
• Richmond
• Greenwich
• Lewisham

Frequently Asked Questions

How Much Does a Garage Conversion Cost UK 2025?

A garage conversion is one of the most cost-effective ways to add living space to your home. Unlike an extension, the structure already exists — you’re simply converting it into usable accommodation. But what does a garage conversion actually cost in the UK in 2025? This guide breaks it down.

Average Garage Conversion Cost UK 2025

Garage conversion costs in the UK typically range from £10,000 to £30,000, depending on the size of the garage, the intended use, and the level of specification. Here’s a rough guide by garage type:

• Integral garage (within the house footprint): £10,000–£20,000
• Attached garage (joined to the house): £12,000–£25,000
• Detached garage (converted to habitable use): £18,000–£35,000

Converting to a bedroom or home office is cheaper than converting to a bathroom or kitchen, which requires plumbing and drainage work.

Cost Breakdown by Room Type

What’s Included in the Cost?

A full garage conversion typically includes:

• Structural work: Replacing garage door with a wall or window/door combination; strengthening the floor slab if required; adding insulation
• Insulation: Walls, floor, and roof to meet building regulations thermal performance requirements
• Windows and doors: New window(s) and an internal door to connect to the main house
• Electrical: New circuit, lighting, sockets, and potentially underfloor heating
• Plumbing: Only if adding a bathroom or kitchenette
• Plastering and decoration: Internal finishes
• Flooring: Typically screed or timber over the existing concrete slab

Additional Costs to Budget For

• Architectural drawings (building regulations): £800–£2,000
• Building regulations fee: £300–£700
• Structural engineer (if floor or structural changes needed): £500–£1,000
• Planning application (if required): £206
• Party wall agreement (if applicable): £800–£1,500

Does a Garage Conversion Need Planning Permission?

Most garage conversions are permitted development and don’t need planning permission. However, planning permission may be required if:

• The conversion changes the external appearance significantly (e.g. adding a dormer, changing the roofline)
• The property is in a Conservation Area
• The original planning permission had a condition requiring the garage to be retained for parking
• The property is a listed building
• You’re creating a self-contained flat or annexe

Always check with your local planning authority or architect before starting work.

Does a Garage Conversion Need Building Regulations Approval?

Yes — almost always. Building regulations approval is separate from planning permission and is required for any material change of use (converting a garage to habitable space). This ensures the conversion meets standards for:

• Thermal performance (insulation)
• Fire safety
• Structural integrity
• Ventilation
• Damp proofing
• Electrical safety

Will a Garage Conversion Add Value?

Yes — typically by more than the cost of the conversion. According to property research, a garage conversion adds approximately 10–15% to the value of a property. For a house worth £400,000, this equates to £40,000–£60,000 of added value from a conversion costing £15,000–£25,000.

The return is best when the conversion creates an additional bedroom, particularly if the house previously had only two bedrooms.

How Long Does a Garage Conversion Take?

• Building regulations drawings and approval: 4–6 weeks
• Construction phase: 3–6 weeks
• Total project timeline: 7–12 weeks

Frequently Asked Questions

Can I convert a detached garage into a habitable room?

Yes, but it’s more complex than an integral conversion. A detached garage conversion may require planning permission if creating a separate dwelling, and will need insulation, heating, and services connecting back to the main house.

Do I need to tell my mortgage lender about a garage conversion?

Yes — you should inform your mortgage lender and buildings insurer before starting work. Failing to do so could invalidate your insurance or breach your mortgage conditions.

Can I lose permitted development rights if I convert my garage?

If your house needed a parking space as part of its original planning permission, losing the garage might technically constitute a breach of that planning condition. Check your title deeds and planning history.

What is the cheapest type of garage conversion?

A basic integral garage converted to a home office or playroom — with no plumbing, just insulation, electrics, and decoration — is the cheapest option, starting from around £8,000–£12,000.

Do I need an architect for a garage conversion?

For most garage conversions, you need at minimum a set of building regulations drawings. Whether you use an architect or architectural technician depends on complexity. Crown Architecture offers fixed-fee packages covering everything from drawings to building regulations approval.

Get a Quote for Your Garage Conversion

Crown Architecture & Structural Engineering Ltd provides full design and building regulations services for garage conversions across London and the South East. Contact us on 07443 804841 or info@crownarchitecture.co.uk for a fixed-fee quote.

Rear Extension Ideas for Terraced Houses UK 2025

Terraced houses are the backbone of the UK housing stock — and they present unique opportunities (and challenges) when it comes to extending. A well-designed rear extension can transform a cramped terraced house into an open, light-filled home that feels twice the size. Here are the best ideas for 2025, along with costs, planning guidance, and expert design tips.

Can You Extend the Rear of a Terraced House?

Yes — terraced houses can be extended to the rear under permitted development rights, without planning permission, if the extension:

• Extends no more than 3 metres beyond the original rear wall (or up to 6 metres under the Neighbour Consultation Scheme)
• Is no higher than 4 metres (single storey)
• Uses materials that match the existing house
• Does not cover more than 50% of the garden

If your terraced house is in a Conservation Area, or if PD rights have been removed, you’ll need planning permission.

Best Rear Extension Ideas for Terraced Houses

1. Open-Plan Kitchen-Diner Extension

The most popular choice — and for good reason. Knocking through the ground floor rear wall to create an open-plan kitchen, dining, and living space is transformative. With bifold doors opening to the garden, you effectively bring the outside in. Key design features:

• Flat roof with rooflights for natural light deep into the plan
• Structural steel to span the opening without columns
• Underfloor heating for a seamless finish
• Kitchen island as the social centrepiece

Typical cost: £45,000–£80,000 (including kitchen)

2. Side Return Extension

Many Victorian and Edwardian terraced houses have a narrow side passage running alongside the kitchen — the “side return.” Infilling this passage with a glazed extension adds perhaps 4–8m² to the kitchen footprint, but the impact is dramatic because the kitchen is no longer hemmed in on three sides.

• Ideal for creating an L-shaped kitchen layout
• Glazed roof over the side return maintains light
• Often paired with a rear extension for maximum impact

Typical cost: £25,000–£50,000

3. Wrap-Around Extension

A wrap-around combines a rear extension with a side return, creating an L-shaped addition. This is the most dramatic ground-floor transformation available for a terraced house — effectively adding a full additional room to the back.

Typical cost: £55,000–£100,000

4. Kitchen Extension with Rooflight

A simple flat-roof kitchen extension with one or more rooflights — without necessarily opening up to the living room — can still deliver a bright, functional kitchen. This is a cost-effective option if your existing layout works well.

Typical cost: £30,000–£55,000

5. Utility Room and WC Extension

A smaller, practical extension to create a utility room, downstairs toilet, or boot room. These add real functionality and are especially valued by families.

Typical cost: £15,000–£30,000

Design Tips for Terraced House Extensions

Maximise Natural Light

Terraced houses are typically narrow and can feel dark, especially the rear ground floor. The single biggest gain from an extension is natural light — rooflights, glass doors, and glazed walls are your best friends.

Think About the Garden View

A rear extension frames your view of the garden. Frameless glazing, sliding doors, or bifolds create a seamless connection. Consider the orientation — a south-facing garden will flood the extension with afternoon sun.

Use Structural Steel Cleverly

Removing the rear wall requires a structural steel beam. An engineer can design a concealed steel that allows you to open up the ground floor almost completely, without a column or pier interrupting the space.

Party Wall Act

If you’re excavating near or on the boundary, or building up to the party wall, you’ll need a Party Wall Agreement with your neighbours. This is separate from planning permission and should be started early — it can take 2–3 months to complete.

Costs Breakdown

Frequently Asked Questions

How much does a rear extension on a terraced house cost?

A typical single storey rear extension on a terraced house costs £35,000–£70,000, depending on size, specification, and location. London prices tend to be 20–30% higher.

Do I need planning permission to extend a terraced house?

Most rear extensions on terraced houses qualify as permitted development. Extensions beyond 3 metres (up to 6 metres) require prior approval via the Neighbour Consultation Scheme. Extensions in Conservation Areas typically need full planning permission.

How long does a rear extension take to build?

Construction typically takes 8–12 weeks for a single storey rear extension. Allow a further 8–16 weeks for design, planning, and building regulations beforehand.

Will a rear extension devalue my terraced house?

No — a well-designed rear extension almost always adds value. In London, a good kitchen extension can add £30,000–£60,000 to the value of a terraced house.

Do I need a structural engineer for a rear extension?

Yes — the steelwork to support the new opening in the rear wall requires structural engineering calculations for building regulations approval. Crown Architecture combines architecture and structural engineering, so you only need one contractor.

Start Your Extension with Crown Architecture

Crown Architecture & Structural Engineering Ltd has completed dozens of rear extensions on terraced houses across London and the South East. We offer fixed-fee packages covering design, planning, and structural engineering. Call 07443 804841 or email info@crownarchitecture.co.uk.

Single Storey Extension Ideas and Costs UK 2025

A single storey extension is one of the most popular home improvements in the UK — and for good reason. Whether you want a bigger kitchen, an open-plan living space, or a home office, a well-designed single storey extension can transform your property and add significant value. This guide covers the best ideas, realistic costs, and everything you need to know about planning and building a single storey extension in 2025.

Average Cost of a Single Storey Extension UK 2025

The cost of a single storey extension in the UK typically ranges from £1,500 to £2,500 per square metre, depending on location, specification, and complexity. Here are typical total costs:

• Small extension (10–15m²): £18,000–£45,000
• Medium extension (20–30m²): £35,000–£75,000
• Large extension (40–50m²): £65,000–£130,000

London and the South East typically cost 20–30% more than the national average. A medium extension in London might cost £50,000–£90,000.

Best Single Storey Extension Ideas

1. Rear Kitchen Extension

The most popular single storey extension in the UK is a rear kitchen extension. By extending into the garden, you can create a large open-plan kitchen-dining-living area flooded with natural light. Key features include:

• Bifold or sliding doors opening to the garden
• Roof lanterns or skylights for natural light
• Island unit as a social hub
• Underfloor heating for year-round comfort

Typical cost: £40,000–£80,000 including kitchen refit.

2. Side Return Extension

Victorian and Edwardian terraced houses often have a narrow side return — the unused alley alongside the kitchen. Infilling this space can add 10–20% more floor area without a large footprint. Side returns are ideal for extending the kitchen and creating an L-shaped open plan.

Typical cost: £25,000–£55,000

3. Orangery or Garden Room

An orangery sits between a full extension and a conservatory. With solid walls, a glazed roof, and high-specification finishes, an orangery creates a year-round living space with a premium feel.

Typical cost: £40,000–£90,000

4. Wraparound Extension

A wraparound extension combines a rear extension with a side return, creating an L-shaped addition that maximises ground floor space. These require more careful planning but deliver dramatic results.

Typical cost: £60,000–£120,000

5. Home Office Extension

Post-pandemic demand for home offices has surged. A dedicated garden office extension — separate from the main house — provides a quiet, professional workspace. Some garden office pods are classed as permitted development if under 15m².

Typical cost: £20,000–£50,000

6. Utility Room and Boot Room Extension

A practical but transformative addition — a dedicated utility and boot room takes pressure off the main kitchen and creates organised storage for muddy boots, coats, and laundry.

Typical cost: £15,000–£30,000

Does a Single Storey Extension Need Planning Permission?

Many single storey rear extensions qualify as Permitted Development — meaning you don’t need planning permission if they meet specific criteria:

• The extension does not extend beyond the rear wall of the original house by more than 4 metres (detached) or 3 metres (semi or terrace)
• Under the Neighbour Consultation Scheme, these limits can increase to 8m and 6m respectively
• The extension is no higher than 4 metres or the eaves of the original house
• The materials match the original building
• The extension does not cover more than half the garden

If your property is in a Conservation Area, Article 4 direction, or is a listed building, permitted development rights may not apply. Always consult an architect or contact your local planning authority before starting work.

What Does the Build Process Look Like?

1. Design: Architect prepares concept drawings and agrees the layout with you
2. Planning: Application submitted if required (8-week decision period)
3. Building Regulations: Technical drawings submitted for structural approval
4. Tender: Quotes obtained from builders
5. Construction: Typically 8–16 weeks for a single storey extension
6. Completion: Building control sign-off and final snagging

How to Add the Most Value with a Single Storey Extension

Not all extensions add equal value. To maximise your return on investment:

• Create open-plan living: Remove the wall between kitchen and dining/living. Open-plan homes command premiums of 5–15%.
• Maximise natural light: Roof lanterns and bifold doors make the space feel larger and are high on buyers’ wishlists.
• Include underfloor heating: A premium feature that adds perceived value and is cost-effective to run.
• Match the existing property: Extensions that look like they belong add more value than those that clash architecturally.

Frequently Asked Questions

Do I need an architect for a single storey extension?

While not legally required, an architect adds significant value — particularly for design quality, planning applications, and building regulations compliance. Most builders will also require detailed drawings before pricing your project accurately.

How long does a single storey extension take to build?

Most single storey extensions take 8–14 weeks on site. Add 8–16 weeks for the planning and design phase beforehand.

How much value does a single storey extension add?

A well-designed single storey kitchen extension typically adds 5–15% to the value of a property. In London, this can equate to £30,000–£80,000 in added value.

Can I live in my house during the extension build?

Yes, in most cases. Contractors will usually maintain a temporary wall between the extension and the main house until the final connection is made.

What is the cheapest type of single storey extension?

A simple lean-to extension with a flat or mono-pitch roof is typically the most cost-effective, starting from around £1,500/m². Orangeries and high-spec glazed extensions cost significantly more.

Get a Quote for Your Single Storey Extension

Crown Architecture & Structural Engineering Ltd specialises in single storey extensions across London and the South East. We handle design, planning, and structural engineering under one roof. Call us on 07443 804841 or email info@crownarchitecture.co.uk for a free consultation.