Extension Builders in Belsize

Name: Extension Builder
Brand: MyBuilder
SKU: extension-builder
Rating: 4 (17 reviews)

Easily find verified Belsize Extension Builders. Just post your job to get quotes from MyBuilder's Extension Builders in Belsize.

Select a service

How it works

Post your job for free

Tell us about your job, and we’ll alert suitable tradespeople in your area. It’s simple and free.

Tradespeople respond

Once your job is posted, you’ll get responses from interested tradespeople through the website.

Review profiles and choose

Browse profiles, work history, and feedback, then choose who you wish to share your details with.

Some of our top rated extension builders in Belsize

3502 Results

Sort by:

Sebek Construction Ltd
Rating: 5 out of 5
Extension Builder in Belsize
Sebek construction family run business for the last 20 years. High quality refurbishment specialits. Kitchens, bathrooms, loft conversion and extension. all work comes complete with public liability insurance.
Get in touch
Latest review:
We have been working with Derek Borkiewicz (Sebek Construction) on a renovation of a garden flat in Little Venice since last autumn. We needed to completely restore the whole flat, including the garden. This was our second renovation project and by this time we knew what we wanted to do, which mistakes to avoid and what to pretend from a qualified builder. We will never stop saying how lucky we have been to find Derek and his team! Derek is not only a professional builder who is very careful to the smallest of the details. He is not only a very good project manager who is constantly checking the work of his men. Derek is a friend who takes on board a project like it is his own project. He suggested the most convenient and best solutions for any problem we came across during the works. There wasn’t a time when he didn’t know what to do to solve a difficult situation (and there are lots of small and big issues coming up in a renovation work) no matter how complicate they were and how long it took to solve them. His availability and his courtesy are incredible above all in a fast running city like London. This is priceless to us. His hard work can be seen in the wonderful result we reached with this garden flat. If we ever decide to work on another project we won’t think twice about working with Derek once again. In fact, now that we found the perfect man to work with, we are looking forward to finding another renovation project to work on! Monica
REWORKS LONDON LTD
Rating: 5 out of 5
Extension Builder in Belsize
Our team comprises eager on-demand workers, with years of experiences, who deliver exceptional services to both residential and commercial customers all around London. Whether you need a painter that will not miss a single mark, or an electrician that assists you in emergencies, we will make sure to send you our specialized and competent workers for all your needs.
Get in touch
Latest review:
Gas Work- 11 Dec 2020
Repaired and very happy!
down town building & Maintenance services ltd
Rating: 5 out of 5
Extension Builder in Belsize
we undertake all type domestic plumbing, Tiling and bathroom and kitchen fitting. we cover all the boroughs of london. our trade men are vastly experienced and hold 12 years experience under their belt.
Get in touch
Razvan Consttruction Ltd
Rating: 5 out of 5
Extension Builder in Belsize
Razvan Consttruction Ltd is a company with a solid team of builders with experience of 20 years!
Get in touch
Latest review:
We had a lot of work done including a brand new roof, whole rear and side extensions. New driveway. Landscaping. Complete fit out works inside. I wouldn’t hesitate to recommend Razvan- he is a complete professional and a really nice guy. Honest and hardworking and takes pride in his work. Out of all of the builders I have used Razvan is the only one I would use again.
Waven.costruction and development ltd
Rating: 5 out of 5
Extension Builder in Belsize
20 years experience in all aspects of plastering. Complete refurbishments, extensions and loft conversions.
Get in touch
Latest review:
Plastering- 21 Jul 2016
Very impressed with John’s work and would highly recommend him. John’s work was very good quality, he recommended practical solutions to problems and had a very positive can do attitude fixing up areas outside of the job I hired him for free of charge. Very happy
Ceca Developments LTD
Rating: 5 out of 5
Extension Builder in Belsize
Hael Construction Ltd, a proud member of the Federation of master builders, is a trusted construction company based in North London, delivering high-quality building services across the region. We specialise in new builds, extensions, loft conversions, renovations, groundworks, electrical installations, and plumbing. With a skilled team of qualified tradespeople and experienced project managers, we provide a complete service from design to completion. Our focus is on quality workmanship, transparent communication, and delivering projects on time and within budget.
Get in touch
Latest review:
Extensions- 23 May 2022
Ceca Developments have done an outstanding work on our side and rear extension project, and we would definitely recommend this company. Firstly, they have offered a really competitive quote for the work and have been very transparent and detailed in regards to how long it will take to complete the project. Sebastjan has been a pleasure to deal with and was very helpful during the project, providing honest and useful recommendations and being available every time we needed anything. All the work has been completed to a very high standard and to the agreed timelines. We did not have to worry about anything during the whole project, which made this a very pleasant experience.
Fornes Limited
Rating: 5 out of 5
Extension Builder in Belsize
No matter what size your requirements are, we provide a complete project management and a full turnkey service from simple kitchen or bathroom make up to more complex projects and skilled finishes like Mediterranean style. No hidden costs and all jobs guaranteed. We speak English and Spanish.
Get in touch
Latest review:
I've used Facundo's team to install a new shower, including wall and floor tiling, massage jets, and concealed shower equipment. Facundo was the person we dealt with at all times, although someone else was assigned to do the job. The quality of the work and finish is extremely good. I was also impressed with Facundo's professional attitude at all times, being very polite and respectful, as well as proactive in addressing any potential issues affecting our planning and execution. Highly recommended.
Valens Construction Ltd
Rating: 4.7 out of 5
Extension Builder in Belsize
We work in construction industry for many years and doing all type of building work which include Side & Rear Extension, Kitchen Refurbishment, Loft Conversion, Convert into HMO, plumbing & electrical, carpentry etc
Get in touch
Latest review:
Kitchen Fitting- 1 Feb 2026
Valens Construction done a good job fixing the kitchen. Made sure every step was done with extra care
London Improvers
Rating: 5 out of 5
Extension Builder in Belsize
I'm a builder (carpenter) with 15 years of experience in England loft conversions and extensions - all building works. Carpentry and joinery is my main profession. I have a bricklayer, electrician, plumber and others on my team who are happy to help. All works done by us coming with warranty and insurance. Dear potential customers don't waste my time if you have budget below £1000 I don't have time for small jobs.
Get in touch
Latest review:
Removal of existing kitchen and fit of new kitchen including belfast sink, washing machine, cooker and hood with external extraction, new floor. Vini and the others worked very hard, were very flexible with timings when problems occurred with delivery of items and after completion were available to check or answer any questions we had.
ALBERTHALL CONSTRUCTION LTD
Rating: 4.7 out of 5
Extension Builder in Belsize
I am and my team are all highly skilled builders with vast knowledge and skills. We have been in the construction industry for 15 years, specialising in extensions, loft conversions and whole house refurbishments. We are new to the MyBuilder portal, so are short on feedbacks. Therefore we will provide references from previous clients.
Get in touch
Latest review:
Extensions- 13 Oct 2023
Sagar and Sanjeev are incredible- they are very diligent and really well versed in what they do! They know what they are talking about and are very friendly and incredible to work with. There was no issue that they weren’t able to help me through when it came to a complete renovation, extension and garden landscaping of my house. They are experts in what they do and they’re the only contractors I want to work with for any other works in the future. Would always recommend them. 100/100!
We Fix Your House Ltd
Rating: 5 out of 5
Extension Builder in Belsize
We Fix Your House is a family-run, small team of experienced industry specialists with many happy clients in and around London. We take pride in our work and ensure that our customers are always happy. So whether you're are looking for a little DIY help, or a complete renovation of your property, we're happy to help. You'll be pleasantly surprised by our competitive prices too, and YES, we can work around your budget.
Get in touch
Latest review:
Plastering- 28 Apr 2019
Great job, very professional
Mark's Amazing Building Company
Rating: 5 out of 5
Extension Builder in Belsize
Mark and his team of 8 have over 100 years of trade experience between them. Each member of the team has honed their craft in a specific trade from bricklaying to plastering, extensions to renovations. Working so close to each other and as a team, they create extensions and renovations to a high standard and always work on one job at a time to ensure a finish of high standards.
Get in touch
Latest review:
Mark and his team did an amazing job on our extension. We will shout it out from the rooftops. They walked us through all aspects of the build and where so friendly and clean. If we ever extend anything else we will look them up.
Alban's A Team Solution
Rating: 5 out of 5
Extension Builder in Belsize
Hi my name is Alban I am a builder. I am honest and hardworking person. I have 18 years experience on general building trade. I undertake all building work, new build houses, new extensions, loft conversion. We also do all refurbishment interior and exterior. All structure and good knowledge of architectural plans.
Get in touch
Latest review:
Carpentry- 20 Oct 2017
nice guy, good comms, very good cartentry
Anjelina
Rating: 5 out of 5
Extension Builder in Belsize
Hello, my name is Krasimir Dimitrov i am a tradesman, i deal with loft conversions, demolitions, new builds, extensions. I have been in the trade for over 10 years.
Get in touch
Latest review:
Demolition- 17 May 2025
The team was great They did everything as they promised The job was finished on time Thanks for the help, it was much appreciated.
AP General Builders
Rating: 5 out of 5
Extension Builder in Belsize
Our company is based on the belief that our customers' needs are of the utmost importance. Our team is committed to meeting those needs. As a result, a high percentage of our business is from repeat customers and referrals. I would be more than happy to showcase the high quality of work I/we pride our self in and would welcome the opportunity to earn your trust and deliver you the best service in the industry.
Get in touch
Latest review:
Extensions- 5 Sep 2019
The builders did an incredible job refurbishing my house. For my house I wanted to break the internal wall to create a bigger living room and also for them to refurbish the toilet. In the beginning they’ve set a period when everything will be done and they’ve stuck to it so they are trustworthy. Seeing the progress, I could definitely tell that they were working incredibly hard and I know that they have been working long hours to ensure that they manage to finish it within the timeframe that they’ve set. I would definitely recommend them.
Barnet Builders
Rating: 5 out of 5
Extension Builder in Belsize
Barnet Builders Amir Gunić I am pleased to introduce my company, Barnet Builders, a trusted name in groundworks and construction services. With over 20 years of hands-on experience in both domestic and commercial projects, I have built a reputation for reliability, quality workmanship, and a professional approach to every job. At Barnet Builders, we own and operate a full range of equipment, including a digger and specialist groundwork machinery, allowing us to deliver efficient and cost-effective solutions. From small residential jobs to larger commercial developments, we pride ourselves on meeting deadlines, maintaining high safety standards, and ensuring complete customer satisfaction. Our services cover all aspects of groundwork, including excavation, site preparation, drainage, landscaping, and more. In addition, we also specialise in house extensions and loft conversions, helping homeowners maximise their living space with practical and stylish solutions. If you are looking for a dependable and experienced partner for your next project, we would be delighted to discuss how Barnet Builders can help you.
Get in touch
Latest review:
Landscaping- 23 May 2026
Amir is absolutely fantastic! If you’re in doubt, don’t be, I can’t recommend Barnet Builders more highly; they’ll definitely be my first call for any work required in the future… and I have high attention to detail and difficult to please. When coming to assess the work required, Amir talked through all of the many different options open to complete the job before we agreed on an approach. The job required two visits with a deadline, and these deadlines were met exactly as promised. Quality of work is A+++, and delivery is above and beyond. Amir even did some additional work that wasn’t his responsibility, but since it helped the overall job, he did it anyway. I’m so pleased to have found Barnet Builders and will continue use them in the future.

Top rated Extension Builders

Our Extension Builders in Belsize, are rated 4 out of 5 based on 17 reviews from customers like you.

Quality screening

Easily find verified local tradespeople. Just post your job to get quotes from tradespeople near you across the UK.

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

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 Belsize 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 Belsize who are available and interested can respond to your post.

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

What are the hourly rates of extension builders in Belsize?

Before getting started with your extension project, it’s important to have a clear budget in place. On average, extension builders in Belsize 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 Belsize extension builders near you on MyBuilder. This allows you to compare what each quote covers and how much your Belsize home extension project is likely to cost.

Find extension builders in Belsize with MyBuilder

Hiring the right extension builder in Belsize 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 Belsize extension builders. Once your job is live, we’ll share it with home extension builders in Belsize who can express their interest.

Step 2: Compare different extension builders in Belsize

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

Step 3: Hire Belsize extension builders with confidence

After gathering all the information and quotes from your chosen home extension builders in Belsize, 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.

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

What to ask a Belsize extension builder before hiring?

Before hiring an extension builder in Belsize or extension building company in Belsize, 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 Belsize?

An extension builder in Belsize 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 Belsize 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 Belsize?

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 Belsize 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 Belsize 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 Belsize

Can an extension builder in Belsize help with planning permission?

Yes, many extension builders in Belsize 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 Belsize handle everything from design to construction?

Many Belsize 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 Belsize help with materials and finishes?

Yes, most extension builders in Belsize 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.