House Extensions in Oxford

Create More Space Without the Cost and Stress of Moving

Knights Builders Oxford has been delivering high-quality house extensions across Oxford and the surrounding areas for many years, helping homeowners unlock the full potential of their properties.

With Oxford being one of the UK’s most desirable and expensive places to buy a home, moving isn’t always the best option. Working with an experienced house extension builder allows you to gain the extra space your family needs while adding significant value to your property, without the upheaval of relocating.

Whether you’re planning a spacious kitchen extension, a new family room, a home office, or a two-storey extension, our experienced team will guide you through every stage of the project-from the initial idea to the final handover.

Bespoke Extensions Designed Around Your Lifestyle

No two homes are the same, which is why every extension we build is tailored to your property, budget, and lifestyle. We construct:

Single-storey extensions
Double-storey extensions
Rear and side extensions
Kitchen and dining extensions
Open-plan living spaces
Utility rooms and home offices

If extending isn’t the right solution, we also specialise in loft conversions and garage conversions, transforming underused space into practical, comfortable living areas.

A Stress-Free Building Experience

Building an extension involves much more than construction. Planning permission, architectural drawings, Building Regulations, inspections, and final certification can all seem overwhelming.

At Knights Builders Oxford, we make the entire process straightforward. As a fully accountable house extension contractor, we work alongside trusted architects, structural engineers, and local building control officers to ensure your project is completed safely, efficiently, and to the highest standards.

Our experienced team keeps you informed throughout the build, delivering exceptional workmanship with minimal disruption to your home.

What sets our house extension builders apart

Anybody can call himself a builder. The thing that counts is if the crew working on your project has done a similar one before, if they show up when they promised to, and if their work looks good five years down the line. These are the things Oxford homeowners consider most often while looking at quotes, so they deserve an honest answer.

We’re a small, local team of house extension builders rather than a large regional outfit juggling dozens of sites at once. That means the person who quotes your job is usually the same person managing it on site, and you’re not passed between departments every time you have a question. For a project happening in your own home – often while you’re still living in it – that continuity tends to matter more than people expect going in.

A few things Oxford clients consistently tell us they valued:

Realistic timelines from day one. We’d rather give you an honest 14-week estimate than a tempting 8-week one we know we’ll miss.
One team, start to finish. The same crew handles groundworks through plastering and snagging – no rotating subcontractors you’ve never met.
Local planning knowledge. Oxford’s conservation areas, listed buildings, and permitted development rules vary street by street. We know which extensions sail through and which need extra groundwork with the council first.
Clear, itemised quotes. No vague lump sums – you’ll see what you’re paying for, from foundations to final fittings.

In case you are trying to compare prices between a number of companies, then it would be wise to ask all the house extension contractors the following three questions: Who will actually be working at your property, what is to be done in case of an unexpected problem, and how is any dispute sorted out after the work? You will get to know a lot more through their answers.

How the extension process works, from first call to completion

Most people who own homes haven’t managed projects like this one before, so they really don’t have a clue what happens, but here’s how it generally goes when dealing with our company:

Initial consultation. We visit your property, discuss what you’re hoping to achieve, and give you an honest view on feasibility and rough budget before any drawings are commissioned.
Design and drawings. We work with architects to produce plans that suit both your lifestyle and your property’s character – particularly important on period homes across Oxford.
Planning and Building Regulations. Where planning permission is needed, we handle the application process. Where the project falls under permitted development, we confirm this formally in writing.
Structural calculations. Any load-bearing changes go through certified structural design, so Building Control sign-off isn’t held up later in the build.
Fixed-price quote. Once drawings and specifications are finalised, you receive a clear, itemised quote – not a rough estimate that grows once work starts.
Construction. Groundworks, structural work, roofing, first fix, and second fix all proceed in sequence, with regular updates so you always know where things stand.
Snagging and handover. A walkthrough concludes the project by sorting out any loose ends before the job is officially completed.

Single storey extensions in Oxford normally take between 10 to 16 weeks on-site time, while double storey extensions can take anywhere between 16 and 24 weeks.

Frequently Asked Question

Q: Do I need planning permission for a house extension?

Not always. Many single-storey rear extensions fall under Permitted Development rights and don’t require full planning permission, provided they stay within set size and height limits. However, this varies by property – particularly for homes in Oxford’s conservation areas or listed buildings. We assess this for you at the initial consultation stage and handle the application if one is needed.

Q: How long will it take to build an ordinary extension to the house?

It takes around 10 to 16 weeks to build a one-story extension, whereas 16 to 24 weeks for two-story extensions. It will depend on the kind of work that needs to be done, the weather conditions, and the building that needs modifications.

Q: What’s the difference between a house extension builder and a general contractor?

A general contractor may take on a wide range of unrelated work – from renovations to repairs to commercial fit-outs. A specialized house extension builder such as Knights Builders Oxford concentrates solely on house extensions, and therefore, the staff has more extensive experience in the idiosyncrasies and requirements of extending a home rather than having general construction knowledge spread thin over various kinds of projects.

Q: Can you manage the whole project, including architects and structural engineers?

Yes. As experienced house extension builders, we coordinate the entire process on your behalf – architects, structural engineers, Building Control, and any specialist trades – so you’re not left managing multiple contacts yourself. You get one point of contact throughout the build.

Q: Can I live in the property during the extension process?

Usually yes. We design work with minimal disruption in mind, timing noise and disruption stages carefully, while trying to make sure that we don’t block access to necessary areas of the property where we can. For larger two-story extensions or full kitchen extensions, we will discuss everything you should know about them during the quoting process.

Q: What should I look for when choosing a good house extension company?

Do not just pay attention to the cost. Consider who will be working on your site, ask for references or past projects of similar scope, check their insurance, and learn how they deal with problems, for instance, unexpected structural difficulties.