Extension Builders in St James

Name: Extension Builder
Brand: MyBuilder
SKU: extension-builder
Rating: 4.2 (20 reviews)

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Some of our top rated extension builders in St James

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ALT’s Builders
Rating: 5 out of 5
Extension Builder in St James
We are a family run business with more than a decade of experience. At ALT’s Builders Ltd we pride ourselves on an efficient and friendly service, and achieve 100% costumer satisfaction ethic. So no matter how big or small your job is we can help. ALT’s Builders Limited is a leading and reputable Construction Company serving around London Ever since we opened for business, we’ve taken a comprehensive approach to construction industry, providing our clients with a wide range of services to cover their needs. our clients are our Number one priority and we go extra mile to make sure they’re completely satisfied. we stand by the excellence of our work and provide clients with personalized attention based on their specific needs. With this service, we’re fully prepared to tackle even the most complex projects and stand by the exceptional quality of our work.
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Latest review:
Loft Conversion- 6 Jul 2026
Brief was a loft conversion + our front driveway completed in East Dulwich, South East London in Q1 2026 and we’d happily recommend Altin from ALTs builders if your in need of a good quality builder: - Competitive price - Good comms throughout - Hard working and extra hours as required to keep project on time - Highly reviewed on checkatrade.com / mybuilder.com company profiles - Overall professional job which we are super happy with When finishing up with us he then started another project down the road off the back of our recommendation and I know they are also very happy with him as a builder!
SZG BUILDING LTD
Rating: 5 out of 5
Extension Builder in St James
18years of experience in the construction sector. I may only offer you quality services and nothing less, with SZG BUILDING LTD you will not have to worry about anything. I specialise in every stage of the construction process, right from the very beginning till the very end, in other words from FOUNDATION to DECORATION in the blink of an eye. I will be very pleased to show my previous work, it may be the final outcome or different stages of various projects. References may be provided.
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Latest review:
Kitchen Fitting- 20 Jun 2019
Really pleased with Slawek and his team and would defiantly recommend them after seeing a professional kitchen fit job which they did for me. They went extra mile to resolve some design issues during the fit, kept the work area clean and tidy and behaved in friendly, polite manner. Nice, reliable team charging very reasonable prices.
Carpenter quality
Rating: 5 out of 5
Extension Builder in St James
CARPENTER QUALITY LTD •SPECIALISED IN EXTENSIONS •LOFT CONVERSIONS •BESPOKE CARPENTRY •KITCHEN & JOINERY •NEW BUILD & REFURBISHMENT
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Latest review:
Carpentry- 11 Jul 2026
Very hrlpful and professional. The new doors looks amazing! I am very pleased with the finish.
SONIM
Rating: 5 out of 5
Extension Builder in St James
SONIM LTD is a South London–based construction and refurbishment company specialising in high-quality residential projects. We deliver loft conversions, home extensions, kitchen and bathroom renovations, flooring installation, plumbing, and full property refurbishments with a strong focus on craftsmanship, attention to detail, and reliability. Whether you're expanding your home, upgrading your kitchen or bathroom, or undertaking a complete renovation, our experienced team is committed to delivering exceptional results — on time and within budget. At SONIM LTD, we believe in clear communication, transparent pricing, and building long-term trust with our clients. Your vision is our priority.
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Latest review:
Restoration & Refurbishment- 3 Nov 2024
Ion and his team were great, they worked really hard and the final result is fantastic, we are really pleased and will use them again! Ion gave lots of helpful advice.
Ev max pro
Rating: 4.7 out of 5
Extension Builder in St James
Reliable. Skilled. Trustworthy. *Qualified Electrician *kitchen fitter *Bathroom fitter *All General Repair *Extension and Pergola I take pride in delivering clean, precise, and high-quality work — on time, every time. Your home’s needs are in good hands. Whether it’s repairs, maintenance, or improvements, I’ve got the skills and dedication to handle it all. You don’t need to worry — just leave it to me. While you focus on your daily life, I’ll make sure everything at home runs smoothly. Trust me to get the job done right, with care and attention to every detail.
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Latest review:
Handyman- 18 Feb 2026
Excellent very amenable
DF Construction
Rating: 5 out of 5
Extension Builder in St James
DFGC are commercial and residential refurbishment specialists. We've created partnerships with high profile companies to complete large scale projects, in the South East of England - shown on my profile. We are known for a wide range of undertakings, from complete refurbishments, extensions, bathrooms, driveways, to name a few. There's very little we can't do, with regards to construction. We're a one stop shop for all your construction needs - we can take your vision and make it a reality.
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Latest review:
Extensions- 13 Dec 2021
Couldn't recommend Domi & Emile enough. They have great building knowledge and kept us informed and up to date throughout the whole building process. The job was finished to a high standard and they even came back free of charge to tie up a few snags a few weeks later. Great builders and a great team!
BLG Development LTD
Rating: 5 out of 5
Extension Builder in St James
flat roof. PRG ROOF. painting. rendering. ceiling. tiling. plumbing. flooring. windows. bathrooms.,Exstenshens,loft
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Latest review:
Extensions- 24 May 2024
We asked BLG to complete a different job to the one we advertised as weren't ready to start it. Instead they completed a 2 bedroom flat renovation, including ripping out and installation of kitchen, removing plasterboard walls, making good, painting and decorating and recarpeting/tiling. Their work and professionalism was great but even better was their attitude. They were always quick to find good solutions to problems, were extremely accomodating, informative, hard working and prices were very reasonable - at no point did I feel I was being ripped off or being treated like a mug, which after completing multiple renovations in the past am well aware of. I wouldn't hesitate to recommend them.
IDL Contractors Ltd
Rating: 5 out of 5
Extension Builder in St James
I am in the building industry for more than 20 years, nevertheless, my company was registered in 2017. Our team is specialized in doing extensions, house conversions and refurbishments.
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Latest review:
I can't recommend IDL highly enough, Lubo and his team were efficient, on time and completed the work quickly with no fuss, plus they gave us a payment plan and time frame that suited us. Our garage conversion has transformed our house, it feels so open and light, thanks Lubo xx
SW Heating & Refurbishments Ltd
Rating: 5 out of 5
Extension Builder in St James
SW Heating & Refurbishments is a local refurbishment company specialising in complete property refurbishments, extensions and loft conversions, new heating systems and boilers. We take pride in all of our work and our aim is to provide you with a quality finish, tailored to your budget. With over 19 years experience, we have built up an extensive team of tradesmen allowing us to provide an outstanding service. We are fully insured and all our work is gas safe and NICEIC certified.
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Latest review:
Conversions - General- 20 Mar 2024
Charlie & Richard did a great job. They visited my property to get an accurate quote. They let me visit another property they are developing which gave me confidence that they were more than capable of my job. They carried out the work quickly and to a high professional standard. Wouldn't hesitate to use them again.
shalom property development ltd
Rating: 5 out of 5
Extension Builder in St James
Shalom Property Development ltd is a small construction company based in the Croydon area. We specialize in property refurbishment, house extensions, loft conversions, garage conversions, etc. We also undertake projects like plastering, painting/decorating, electricity, plumbing, tiling, flooring(laminate, wood, bamboo), bricklaying.
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Latest review:
Plastering- 6 May 2025
Amazing guys. Hardworking, tidy, professional. They worked in our house for 3 months and we were super happy with the work and everything. We invited them to do more work later on. 100% probably the most sincere and trustworthy builders we met. Only them. No one else from now on.
Dmytro Dochynets
Rating: 5 out of 5
Extension Builder in St James
Experienced bricklayer. Skilled in brickwork, garden walls, fences and repair jobs. Reliable, tidy and delivering quality work on time.
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Latest review:
Bricklaying- 30 Oct 2025
Dmytro did fantastic job rebuilding garden wall in our landscaping project. Highly recommended
P&T Property renovation LTD
Rating: 5 out of 5
Extension Builder in St James
LND Development ltd was established by a Polish builder. As a business we pride ourselves to provide a very experienced, hard working, friendly and loyal workforce. We provide a professional and experienced service at very competitive rates.
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Latest review:
Pawel and the team did a fantastic job. The bathroom looks superb and the whole team took time to finish the job to a very high standard. There was a narrow timeframe in which to do the work and this was met (despite more effort than first thought with respect to strengthening the floor). Pawel was easy to deal with and contacted me after the job to ensure everything ok. Highly recommended.
Rcm Buildrs
Rating: 5 out of 5
Extension Builder in St James
RCM Builders is an insured construction company which offers a multitude of services. Loft conversions, extensions, painting, plastering, fencing, building renovations, and bricklaying are a few specialities we covers. We have over 28 years worth of experience and are well versed in providing high quality work, great customer service, great costumer satisfaction and great communication.
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Latest review:
Conversions - General- 7 Mar 2023
Have completed the job extremely well. Did a new door opening. Door fittings and plaster work . Very good finish. On time. Polite. Very pleased. Would hire again.
Vadym Kutsak
Rating: 3.7 out of 5
Extension Builder in St James
I have 7 years in basement, underpinning, extension. Was working at company "Hughes design&build" Have good knowledge in job
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Latest review:
Groundwork & Foundations- 30 Mar 2026
Vadym did a very professional job. He is a good communitcator , and left the site clean and tidy.
Cepele Construction
Rating: 5 out of 5
Extension Builder in St James
Introducing Cepele Construction Experience and Past Jobs: Cepele Construction has earned a reputation for exceeding expectations and delivering high-quality results. We have successfully completed numerous projects, such as the ones for James Smith and Teresa McTavish, ensuring that each client's unique vision is realized with excellence and professionalism. Where We Can Work: We operate primarily in London and the surrounding areas, offering our services to clients who need reliable and top-quality construction work. Special Skills: Our expertise includes loft conversions, customized construction solutions, and exceptional project management, ensuring every detail meets our high standards. Why Hire Us: At Cepele Construction, we are committed to providing top-quality services tailored to each client's needs. Our dedication to excellence and client satisfaction sets us apart as the best choice for your construction projects. For more information, visit our website at Cepele Construction
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Renovations.Tm
Rating: 5 out of 5
Extension Builder in St James
We are an experienced and reliable company specializing mainly in extensions, basements, conversions, skylights. We can carry out renovations or building works to your dream home. As we say, Well Done Is Better Than Well Said, come and check us out now !!!
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Latest review:
Tomasz and team did various jobs for me (wooden floor, skirting boards, acoustic wall and floor insulation, plastering, painting, electric work etc). Top finish and workmanship, extremely professional and reliable, friendly, helpful, considerate, punctual, honest, tidy worker.

4.2

Top rated Extension Builders

Our Extension Builders in St James, are rated 4.2 out of 5 based on 20 reviews from customers like you.

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What types of services are offered by local extension builders in St James?

Building an extension is a major milestone for any home. It’s not just about adding extra space, it’s a big step that can transform how you live day to day, opening up new possibilities for comfort, lifestyle, and family needs.

This is why it’s so important to find the right extension builders in St James for you. They can help with a variety of tasks and projects, including:

Extending your home with an extra room
Two+ storey extensions
Adding partition walls to create more rooms
Building annexes or external structures

To find the right extension builder near you, simply post your job on MyBuilder. Explain the type of help you’re looking for, and then home extension builders in St James who are available and interested can respond to your post.

Browse profiles, read customer reviews and get quotes from your chosen St James extension builders, all before you decide who to hire.

What are the hourly rates of extension builders in St James?

Before getting started with your extension project, it’s important to have a clear budget in place. On average, extension builders in St James will charge between £16 and £42 per hour.

Single-storey rear extensions cost between £20,000 and £60,000 depending on size and finish.
The cost of double-storey extensions, which add more space and value, can range from £100,000 to over £170,000.
Larger wrap-around extensions that combine multiple extension types can range from £40,000 to over £120,000.

The cost of an extension will vary depending on your property. For instance, extending in certain areas may require structural adjustments to ensure stability, which can increase your material and labour costs.

To get an accurate price for your home extension, request detailed quotes from several St James extension builders near you on MyBuilder. This allows you to compare what each quote covers and how much your St James home extension project is likely to cost.

Find extension builders in St James with MyBuilder

Hiring the right extension builder in St James with MyBuilder couldn’t be easier. Just follow these simple steps:

Step 1: Post your extension project on MyBuilder

Whether you’re planning a single-storey extension, a loft conversion, or adding a new room, post your job on MyBuilder to find local St James extension builders. Once your job is live, we’ll share it with home extension builders in St James who can express their interest.

Step 2: Compare different extension builders in St James

When you start receiving interest, review profiles of local St James extension builders, check their previous work, and read real customer reviews. Ask about timelines, materials, and request detailed quotes.

Step 3: Hire St James extension builders with confidence

After gathering all the information and quotes from your chosen home extension builders in St James, compare their experience, guarantees, and costs before choosing who to hire.

You’ll also have confidence knowing that every tradesperson on MyBuilder is verified through several checks, including:

ID verification: When a tradesperson joins MyBuilder, we ask for a valid ID, such as a passport, ID card, or eIDAS certificate.
Company verification: For tradespeople operating under a company, we make sure every tradesperson has a registered business.

Did you know? Our continuous monitoring and complaints process ensures that tradespeople who don’t meet our standards are promptly removed from MyBuilder’s platform.

St James extension builders are ready to help. Use MyBuilder today to find the right professional for your home extension.

What to ask a St James extension builder before hiring?

Before hiring an extension builder in St James or extension building company in St James, ask a few key questions to make sure you’re choosing the right professional for your home extension project.

What qualifications and experience do you have as an extension builder in St James?

An extension builder in St James should have a strong track record with similar projects and relevant building qualifications or trade memberships, such as the Federation of Master Builders (FMB) or TrustMark.

Will my home extension meet all building regulations and planning requirements?

Your St James extension builder should ensure the project complies with Building Regulations and, where necessary, handle or assist with planning permissions. Ask how they manage building control inspections and what documentation you’ll receive once the project is complete.

What experience do you have with similar extensions in St James?

Ask to see examples of their previous work, or view examples of their work on MyBuilder. Ideally projects similar to yours in scale and design. This helps you assess the St James extension builder’s ability to deliver a result that meets your expectations.

How long will the extension take to complete?

Extension project timelines can vary depending on size, complexity, and weather. A typical single-storey extension might take around 8 - 12 weeks. Request a detailed schedule so you know what to expect and when key milestones will be reached.

Do you offer a guarantee for your work? Most St James extension builders offer a guarantee or warranty on their work, often between 1 and 10 years depending on the project and materials used. This gives you assurance that any issues will be resolved after completion.

If you still have questions about the professional you are looking to hire, we have a full detailed guide on hiring the right builder here.

FAQ: Common questions about home extensions in St James

Can an extension builder in St James help with planning permission?

Yes, many extension builders in St James can guide you through the planning process. They can help prepare drawings, advise on local requirements, and liaise with your local council to ensure your project meets all necessary regulations.

Can an extension builder in St James handle everything from design to construction?

Many St James extension builders offer full design-and-build services, managing both the architectural planning and construction stages. Ask your builder whether they can provide a complete package or if you’ll need to hire an architect or designer separately.

Will an extension builder in St James help with materials and finishes?

Yes, most extension builders in St James can source materials and offer advice on finishes that suit your design and budget. You can also choose to supply certain materials yourself, just make sure this is agreed upon before work starts.