Ultimate Beginner’s Guide to Building a House Extension in the UK

How much does it cost to build a house extension in the UK?

Have you noticed the latest trends among homeowners and developers, who are increasingly adding more space (home extension) to their properties and maximizing every inch available?

While house extensions are gaining popularity for their ability to enhance living spaces and property value, navigating the process can be daunting without proper guidance.

Understanding what house extensions entail—from regulatory hurdles to design and construction—can make a significant difference in your project’s success.

Home extensions are not just about adding extra rooms; they can transform your living experience and increase the value of your property.

Benefits such as creating additional living space

They offer benefits such as creating additional living space, improving functionality, accommodating growing families, and enhancing property aesthetics.

However, embarking on an extension project requires careful planning and professional expertise.

Architects and builders play crucial roles in ensuring your extension meets both your needs and regulatory requirements, navigating complexities like planning permissions and building regulations seamlessly.

Given the evolving regulatory landscape, it’s prudent to rely on professionals who can guide you through every step—from initial concept to final construction.

YOOP Architects, for instance, offers free professional consultations to help homeowners navigate these complexities effectively.

In this comprehensive guide, we will walk you through everything you need to know about building a house extension in the UK, exploring different types and sharing expert tips to assist you in choosing the best extension type for your home.

Tag along as we share expert tips on building house extensions and transform your property into the space you envision.

 

Expanding your living space with an extension is an exciting way to enhance your home’s functionality and comfort. But before the building commences, a well-planned approach is key.

We’ll navigate the process step-by-step, from initial planning and design considerations to navigating regulations and construction.

Whether you dream of a contemporary kitchen extension or a light-filled garden room, this guide empowers you to embark on your extension journey with confidence!

Step 1: What type of extension do you need?

If you’re thinking about build an extension to your home. Then it’s a good idea to start by considering why you want to add an extension and what the function of the new space will be. This will help to determine the type of extension required (single storey/two storey/loft conversion etc) and the design of the final layout of your home.

Sometimes there may be multiple ways to achieve your objective. Accordingly, If you’re not entirely sure how you want to extend your home or would just like some alternative ideas.  Yoop Architects can take a measured survey of your property. Similarly then draw it all up in 3D and create sketches to show sometimes five or six options to achieve your desired result.

Step 2: Who will develop an extension of your new layout?

You don’t have to work with an architect to design your extension. Rather you can choose to design it yourself, opt for a build and design company.  Particularly, work with an Architectural Technologist or anyone else that has the knowledge and expertise to design your extension.

However, there are many advantages to hiring an architect to build an extension over another type of designer. For example, all architects must be registered with the Architects Registration Board (ARB) Which means they are obligated to follow the ARB code of conduct and you have more rights if something were to go wrong at any stage.

Additionally, a local architect should have a good understanding of the local authorities guidance. Moreover, planning policies and also help to make sure that the building conforms to UK Building Regulations.

The disadvantages of hiring an architect are mainly their fees. However, a good architect will be working to help you keep within budget and their expertise allows them to see possibilities that you may not have thought of, potentially helping you to save money overall.

Sometimes there may be multiple ways to achieve your objective – Yoop Architects can take a measured survey of your property and create sketches to show sometimes five or six options to achieve your desired result.

– Yoop Architects

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Step 3: Choosing an extension builder

After decades in the construction industry, Yoop Architects have worked with some great builders. Certainly we can help you find someone who you can trust with your home. We can introduce you to a few, or you might have one or two of your own in mind.

When choosing a builder, it’s important to find someone who’s reputable, reliable. Obviously, that you get on with on a personal level. They should be able to offer a guarantee/warranty and formal, detailed quotations/contacts. For more tips, check out ‘Tips For Choosing A Builder’ to find the right builder to turn your plans into reality.

Step 4: Planning Permission & Neighbours

As long as your house is quite original and unmodified, a lot of home extension/conversion projects come under permitted development (which means you don’t need to apply for planning permission – it’s granted automatically). This means you can just start building. However, we recommend that you apply for a lawful development certificate to prove that the work is covered by permitted development.

If your project is not covered by permitted development. Then you’ll need to apply for planning permission. To apply for planning permission, you need to make an application to your local planning authority or via the Planning Portal online application service. (You don’t need to make the application yourself. Yoop can apply for planning permission on your behalf and chase the planning authority up until we get the OK so you don’t have to worry about it)

It’s a good idea to have a chat with your neighbours at this stage about your extension.  Both as a courtesy and to see if there are likely to be any potential problems/objections. Also, if your extension involves building or digging foundations within 3m of a shared wall or other foundations. Then you may require a Party Wall Agreement. This is an agreement which means that your neighbours have given consent to the work being carried out and will protect you and your neighbour if anything goes wrong.

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Step 5: Building Regulations

The Building Regulations are minimum standards for design. Additionally, construction and alterations to virtually every building to ensure the safety and health for people in or about those buildings. They cover aspects such as fire safety, insulation, drainage and access.

All extension work requires building regulations approval.  However, you do not need to get approval yourself if you use a builder registered with a competent person scheme.

Step 6: How much will your new extension cost?

For build costs, if you worked out a square meter at £1500, that’s a good base price for basic quality. So, for an average single storey extension of 20 square metres, the build cost would be from £30,000 for basic quality

Interior fit out costs vary greatly depending on the function of the room and the quality of appliances. But we’ve created a Home Extension Cost Guide to give you a rough idea of prices.

Professional fees such as getting a measured survey, planning and construction drawings, architect design fees, structural engineer fees, contract/project management.  Along with VAT work out at around £12,000 for an extension of 20 square metres at a build cost of £30,000 (these may not all be necessary depending on what you are planning).

Permission fees, agreements and additional reports come to around £2000. All together, for a single storey extension of 20 square metres of basic quality, this will give you a minimum spend of £44,000 including most fees, but excluding interior fit-out costs.

If you have any questions about planning and building an extension, or just questions about creating your dream home in general, go ahead and book a free call below with Yoop.

Common Types of House Extensions in the UK

 

House extensions in the UK vary widely to suit different property layouts and homeowner preferences:

Single-storey extensions

Extend the ground floor horizontally, commonly used for expanding kitchens, living rooms, or creating open-plan spaces that connect seamlessly with outdoor areas.

Double-storey extensions

Add extra floors vertically, suitable for increasing both living and bedroom space significantly. This type of extension can transform a property by adding bedrooms upstairs while expanding living areas downstairs.

Conservatories

Typically featuring glass or polycarbonate structures, conservatories serve as garden rooms or sunlit spaces, perfect for relaxing, dining, or growing plants year-round.

Orangeries

Similar to conservatories but often incorporating more solid construction with brick pillars and less glass, providing a more permanent extension that blends well with traditional architecture.

Loft conversions

Convert underutilized attic spaces into functional living areas, such as bedrooms, home offices, or playrooms, utilizing existing roof space to maximize living space without extending the property’s footprint.

Wrap-around extensions

Combining side and rear extensions to create a wrap-around effect, enhancing both ground floor living spaces and upper-floor bedrooms or offices.

Over-structure extensions

Building over existing single-storey structures, such as garages or outbuildings, to add bedrooms, offices, or self-contained annexes, maximizing available land space.

Basement conversions

Converting existing basements or excavating new ones to create habitable spaces below ground level, such as additional living rooms, gyms, or entertainment areas.

Legal and Planning Considerations

 

Navigating legal requirements and planning permissions is critical when undertaking a house extension project in the UK:

 

• Permitted Development Rights (PDR)

Certain minor extensions may proceed without full planning permission, subject to specific criteria regarding size, location, and impact on neighbors.

 

• Planning Permission

Larger extensions or those altering a property’s appearance typically require planning permission from local authorities to ensure compliance with zoning regulations and neighborhood aesthetics.

 

• Building Regulations

Adherence to building regulations ensures structural integrity, energy efficiency, and safety standards throughout the construction process, overseen by local building control authorities.

Understanding these considerations enables homeowners to plan and execute house extensions effectively, enhancing their living spaces while adhering to legal frameworks designed to maintain community and environmental standards.

How Yoop Architects Can Help You Build the Perfect Home Extension

At Yoop Architects, we realise that home extension is a tremendous commitment to plan wisely, design, and execute effectively. You may want to add another bedroom or expand your kitchen, convert part of your home into an office, or simply add on to your living spaces. Myriad possibilities await you, and we have worked every step of the process with you.

Here’s how we can help with making your house extension stylish, practical, and economical.

Bespoke Design Solutions

Every house and every homeowner is different, and so your extension should also showcase your individual flair and practical necessities. All our architects record what you want to have in an extension, both in conception and design, to allow the construction to substantiate the living spaces within your existing home.

We focus on:

Space Maximisation or Spatial Efficiency: The best planning and design for optimum functional performance.

Visual Continuity: stylish designs blending with your existing property.

Energy Efficiency: Provided with many sustainable answers to lessen your domestic environmental imprints. Concept through to execution, we produce bespoke solutions for better living, increasing the value of your property.

Planning and Statutory Assistance

There are few things that can be more daunting than running around for planning permissions and building regulations. At Yoop Architects, we take on such burdens for you, making sure that your work is covered in every legal sense possible.

Council Planning Permission Applications: If your extension is going to need Council approval, we will prepare, submit, and handle the entire stream of documents needed.

Permitted Development Advice: We will check whether the project falls within permitted development rights, allowing you to carry it out without formal permission.

Building regulations compliance concerning safety, structural, and energy efficiency.

In all ways legal and regulatory, we save your time and costly errors by enabling an easy approval process.

Project Management

In putting up a good home extension, coordination between people like builders, engineers, and surveyors becomes a key issue. Project management, therefore, takes care of everything in the house from beginning to end for a smooth running operation of the entire process.

We provide:

Construction Oversight: Timelines, quality control, and contractor coordination.

On-Budget Monitoring: Keeping hold of costs but not on quality.

Regular Progress Updates: Keeping you updated throughout the project.

We take the stress out of it by putting it in the hands of professionals who know what they are doing. 

Final Thoughts

A home extension is worth the investment. It improves your quality of life and adds value to your home. However, making it work needs careful planning, skilled designing, and good management. With Yoop Architects, you can expect an extension customised to fit your needs, without a hitch. 

Are you thinking about extending your house? Call Yoop Architects today and tell us about your project so that we can help realise your vision!