Side Return Extension Cost

A side return extension is an excellent strategy for maximising underused space at the side of your house, transforming it into valuable living space that can enhance your home’s functionality and value. This upgrade is particularly beneficial for terrace houses, which commonly feature narrow side returns that serve little purpose in their original state.


Such extensions are a savvy choice not only for their ability to repurpose useless areas but also for the potential to incorporate a new kitchen, elevating your home’s entertainment and living areas. However, navigating the cost of a side return extension can be challenging, given the factors influencing final expenses, such as architect fees, building regulations, and the need for a party wall agreement with neighbours.


In this guide, we delve into what homeowners might expect regarding the average cost of a side return extension. Whether you are located in London or outside London, looking to add a single-storey extension or considering a more complex double-storey extension, this article aims to equip you with the essential knowledge to take the next steps. 

side return extension cost
cost of side return extension

Introduction to Side Return Extensions

Defining the Side Return Extension

Side return extensions use the narrow gaps found near terraced or semi-detached properties to transform them into valuable, usable space. This approach typically helps square off existing home layouts while breathing new life into dark and underutilised corners of home life.


Though an extension might appear minor on paper, its impact on overall proportions in connected rooms such as kitchens can be substantial. By expanding into this space, homeowners can experience more spaciousness, light, and enjoyment in their living spaces.


The Popularity of Side Return Extensions in London

Side return extensions have become an attractive home improvement solution in London for several compelling reasons, including:


  • Expanding the living areas: Homeowners can significantly expand their living areas by creating more room for a kitchen or dining space that suits modern living needs.
  • Enhancing natural lighting: By installing features like glass side return extensions or skylights, natural light is brought into interior spaces, making them feel brighter and more welcoming.
  • Enhancing property Value: Installing a side return extension can add great value to a property by increasing its aesthetic and functionality, making it more desirable among potential buyers.
side extension cost

Comprehensive Cost Breakdown of a Side Return Extension

Like any house extension cost, the quality of materials and finishes used, whether a single- or double-storey extension, all impact the price. Geographic location also plays an influential role, with London typically costlier than other parts of the UK.

Here is a detailed breakdown of the costs associated with different types of side extensions:

Type of Side Extension Low Cost High Cost Average Cost
Small, single-storey side return extension cost £30,000 £45,000 £37,500
Small double-storey side return extension cost £45,000 £65,000 £55,000
Side return kitchen extension cost £5,000 £14,000 £9,500
Side return extension cost per m² £1,500 £4,500 £3,000
Glass side return extension cost per m² £3,000

Average Costs of Side Return Extensions

Outside London, costs per square metre can range between £1500 and £2400 per metre; in comparison, London experiences higher costs – reaching up to £4,500 due to factors including increased labour and material costs.

cost of side extension

Single-Storey vs Double-Storey Side Extensions

The single-storey extension cost for side extensions is around £30,000 to £45,000, with an estimated average cost of around £37,500. For double-storey extension costs, you’re looking at £45,000 – £65,000 with an approximate average of £55,000.

Kitchen Side Return Extensions

Popular among homeowners looking to add functionality and flow into their kitchen without going the full remodel route, side return kitchen extensions are an economical and straightforward solution ranging from £5,000 to £14,000, typically costing approximately £9,500.

Financial Planning for Your Side Return Extension

Budgeting for Your Side Extension

An extension project requires careful financial preparation to avoid unpleasant surprises in terms of costs. Begin by measuring the area you intend to extend and researching average costs per square metre in order to establish an affordable budget.

Cost Per Square Metre Analysis

When calculating the cost of a side return extension, location plays a crucial role. Outside London, homeowners might expect costs to range between £1,500 and £2,400 per square metre. However, the cost of a side return extension in London, due to higher labour and material costs, is higher – up to £4,500 per square metre. This variance highlights the importance of regional cost considerations in your budgeting process.

cost of side return extension london
side return extension cost london

Hidden Costs and Considerations

Additional costs are crucial in budgeting for your side extension. Security enhancements such as outdoor lights, CCTV, locks, and alarms might need an electrician or specialist, costing £150-£200 daily.


Internal fittings, like shelves or bespoke cupboards, require a carpenter or kitchen fitter, with costs starting at £100 per day and basic cupboards from £100. Opting for second-hand cupboards can save money.


Guttering and drainage, vital for water management, could cost around £10 for a water butt and £150 for guttering, often installed by a builder or homeowner. Early planning for these costs ensures a smooth project completion.

Legal and Planning Considerations in Side Extension Costs

Planning Permission and Regulations in London

In London, the scope of your side extension can sometimes fall within Permitted Development rights, eliminating the need for formal planning permission. This concession aims to simplify smaller home improvement projects, making it easier for homeowners to extend their living space.


However, even without the need for planning permission, every house extension, including a side return extension, must comply with building regulations. These regulations ensure the safety, energy efficiency, and accessibility of the new structure, covering everything from structural integrity to fire safety. Adherence to these rules is crucial for the legality and long-term success of your project.

The Necessity of a Party Wall Agreement

When planning a side extension, particularly in densely populated areas like London, the party wall agreement becomes significant. If your planned extension involves work on or near a shared boundary, or if it requires digging near a neighbouring building, you will likely need this agreement.

how much does a side return extension cost

Timeframe and Process of Building a Side Return Extension

side return extension london

Typical Duration for Completing a Side Return Extension

The journey to extend your living space with a side return extension can vary in length, but on average, it takes around 12 weeks to complete. This time can shift depending on the complexity of your project, the size of the extension, and the specific requirements for building work.

Step-by-Step Process Overview

Before the first brick is laid, ensuring you have planning approval and building regulation-friendly plans developed by an architect is essential. Here is a concise guide to the building process:


  1. External Construction:
    • With permissions in place and your team ready, the first phase includes site preparation, foundation laying, external walls, and roof construction, and installing windows and doors. Expect to organise scaffolding, skips, and other necessary equipment during this stage.
  2. Interior Work:
    • This phase focuses on reconfiguring the internal space, removing old fixtures, and installing insulation to meet building regulations.
  3. Internal Fit-Out:
    • The internal fit-out includes plastering, flooring, plumbing, and electrical work, setting the stage for new kitchen installations or other specific living space enhancements.
  4. Interior Decor:
    • Finally, the vision comes to life with painting, decoration, and the addition of light fixtures and furniture to match your extension ideas.
  5. Final Inspections:
    • To conclude, address any snagging issues and arrange final inspections to ensure compliance with all safety and building regulations.
how much for side extension

Enhancing Your Property with a Side Return Extension

london side return extension

The Value Added to Your Home

An investment in a well-planned and thoughtfully constructed side return extension can significantly increase the value of your property. Expanding living areas or adding rooms not only adds functionality and aesthetic appeal, but can also significantly boost market value.


An addition could add as much as 25% value to your home. For instance, an extension on a property valued at £150,000 could see it increase in worth to approximately £190,000. That equates to an approximate return on investment of about 10% over its cost.


However, poorly executed projects may fail to add value and could actually detract from it, underscoring the importance of careful planning, selecting suitable materials, and engaging skilled professionals in your extension project to ensure its success.

Side Return Extension as an Investment

Viewing a side return extension as an investment rather than just an expense can shift how you see its value to your property. This investment significantly enhances your living space, improving both the quality of life and the attractiveness of your property on the market.

Choosing the Right Construction Company: Introducing Fittra

At Fittra, we are a construction company that is backed by our registration with NHBC and a robust team comprising partner architects, engineers, consultants, and designers. Offering both commercial and residential construction services at competitive prices, Fittra brings over a decade of quality-focused experience in home extensions. Our commitment to detail on various projects sets us apart, providing a comprehensive solution for those in and around London seeking reliable building companies.

how much is a side return extension
side return cost

Why Fittra Stands Out in West London

Fittra distinguishes itself through a host of free consultancy services, full architect and structural design, project management, planning permission submission, development research, and legal advice. Our approach ensures clients receive all-inclusive support throughout their building journey.

Comprehensive Services Offered by Fittra

The range of services we provide covers every aspect of building work, including all types of house extensions in London (dormer, hip-to-gable, Velux, shell, and more), new builds, house renovations, refurbishments, kitchen fitting, bathroom fitting, as well as windows and doors installations. This extensive offering caters to varied client needs, making Fittra a versatile choice for construction projects.

The Benefits of Choosing Fittra for Your Side Return Extension

Opting for Fittra for your side return extension brings numerous advantages:


  • Free schedule of works and detailed cost breakdowns ensure transparency.
  • An upfront deposit of only 10%.
  • Accreditations from NFB, FMB, NHBC, TrustMark, and Considerate Constructors underscore our industry recognition.
  • Clients benefit from trade discounts.
  • Comprehensive insurance coverage, including £5M public and products liability and £10M employer’s liability insurance, offers peace of mind.


Choosing Fittra means partnering with a company that not only delivers value for money but also ensures a stress-free process from conception to completion. Whether it is a new extension, renovation, or kitchen diner transformation, our expert team guarantees to extend your living space with precision and care.

kitchen side return extension cost

Client Experiences and Portfolio

side return extension costs

Case Studies: Successful Side Return Extensions by Fittra

Experienced in London and beyond, we specialise in side return extensions that not only meet, but exceed client expectations. From improving Victorian terraced homes to modernising contemporary residences, our portfolio speaks for itself in terms of quality, value, and aesthetics.

Testimonials and Client Feedback

One of our clients shared their experience working with us on an extensive renovation project, featuring one of its highlights–a rear extension to build a new kitchen equipped with lantern roof lights. Here is what they had to say:

“The professionalism displayed by Ivan and his team was exceptional. They managed to complete the work not just within the agreed time but also ensuring our complete satisfaction. What stood out was the clarity and ease of understanding their breakdown quotes, making the entire process seamless. We highly recommend Ivan, Igor, and their team for their outstanding work. Great job!!! – Isleworth”

Starting Your Side Return Extension Project with Fittra

Initial Consultation and Design Process

A side return extension project begins with a detailed and informative initial consultation with Fittra. During this crucial first step, we aim to understand your vision by asking general questions about your project, including its location and type.

To ensure we have all the necessary details to move forward effectively, we schedule a site meeting to gather comprehensive information about your project. For those who have not secured an architectural design, our experienced team is ready to assist and guide you through this pivotal phase, making the journey towards your new extension a seamless one.

victorian terrace side return extension cost
cost of a side return extension

Understanding Fittra's Smooth and Stress-Free Approach

Fittra’s approach to building your side return extension is designed to be as smooth and stress-free as possible. Once we have the architectural and structural designs, either provided by you or developed with our help, we embark on preparing a detailed proposal. This proposal, typically spanning 12 to 18 pages, breaks down each item and type of work separately for clear understanding, highlighting what is included and excluded to ensure transparency.


After presenting our proposal, we anticipate your questions and are ready to discuss every detail to ensure your complete understanding. We believe in giving you space and time to make an informed decision without any rush. Choosing the right contractor is crucial, and we want you to feel confident and focused during this decision-making process.


The building process is initiated with another site meeting to sign the contract, introduce your project manager, and agree on the payment schedule, which includes a modest 5% deposit. We also provide a list of discounted suppliers to help you save on costs without compromising on quality.


Upon completion of the renovation, Fittra guarantees that the project meets our high standards. We address any snagging issues promptly, provide warranties for new products, and issue the necessary certificates, ensuring you are ready to enjoy your enhanced home with peace of mind.


Recap of Side Return Extension Costs and Value

The costs and values associated with its improvements are integral to any property investment. From new kitchens in Victorian terraced homes to expanding living space, investing in such projects can substantially add value. Costs should range between £1,500 and £2,400 per square metre in areas outside London due to higher labour and material rates in London; however, costs could reach as high as £4,500 per square metre.


Side return extensions offer many advantages that go far beyond costs. Aside from increasing living space and market value, they allow you to personalise your home to fit your lifestyle. The right architect and construction team can turn even all types of side returns into invaluable value additions to your home.

cost side return extension
side extension cost

Next Steps with Fittra for Your Dream Side Return Extension

Taking the next step towards your dream side return extension with Fittra means embarking on a seamless and stress-free journey. Fittra’s comprehensive service package, from free consultancy to detailed cost breakdowns, ensures transparency and confidence from the start. Our experienced team of architects, engineers, and designers offer end-to-end solutions, tailoring each project to the homeowner’s vision and specifications.


Choosing Fittra not only guarantees a quality house extension but also an investment into your property’s future. With accreditations like NHBC, FMB, and TrustMark, alongside £5M public and products liability insurance, your project is in safe hands. Our commitment to value for money, supported by trade discounts and a minimal 10% deposit, reflects our dedication to your satisfaction and the success of your project.


Ready to extend your kitchen or living space? Contact Fittra today to schedule your initial consultation and take the first step towards transforming your home with a side return extension that exceeds expectations.



Why Work With US

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at all stages

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with project manager

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liability insurance

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of works

Integrated, In-house Team Will Work On Your Project

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Benefits from our trade discounts
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£5M public & products liability
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10% only deposit payments
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Detailed cost breakdown

In the End You Will Get




Our Projects

FAQ: Answering Your Key Questions

How Much Does a Side Return Extension Cost in 2024?

In 2024, the side return extension cost can range from £1,500 to £2,400 per square metre outside London and up to £4,500 in London. The side return extension cost will always be higher because of its environment.

How to Ensure a Cost-Effective Side Return Extension?

To ensure a cost-effective side return extension, get three to five quotes, choose value for money materials, and work with an experienced architect to avoid unnecessary expenses.

What is the Average Timeline for Completing a Side Return Extension?

The average timeline for a side return extension is about 12 weeks, but this can vary based on the complexity of the design and any unforeseen building work delays.

Can Side Return Extensions be done Without Relocating?

Yes, side return extensions can often be completed without the need to relocate, especially if the construction work is limited to a single storey and planned to minimise disruption.

What are the Unexpected Costs in Side Return Extensions?

Unexpected costs in side return extensions may include additional planning permissions, unforeseen building regulations requirements, or structural changes not initially anticipated.

Do Side Return Extensions Require Special Insurance?

No, but you will need to update your home insurance as the rebuild costs of your house have increased.

Design trends for side return extensions in 2024 include glass roof installations to maximise natural lighting, open-plan kitchen diners and seamless indoor-outdoor living space connectivity.

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