Extension Builders in Belsize

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

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Some of our top rated extension builders in Belsize

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DARDANIAL LIMITED
Rating: 5 out of 5
Extension Builder in Belsize
Dardani. al Limited Experts in RC frame construction, deep drainage, basements, groundworks, steel fixing, refurbishments, loft conversions, brick & block work, and underpinning. Delivering quality, precision, and reliability on every project — from the ground up, Tarmac takes on all aspects of ground works, including structure, landscaping, civil engineering, and fencing
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CM Building LTD
Rating: 5 out of 5
Extension Builder in Belsize
At CM Loft Conversions, we specialise in luxury loft conversions, home extensions, and full refurbishments for both residential and commercial properties across London. Our dedicated team is renowned for transforming spaces with unparalleled craftsmanship and meticulous attention to detail. Whether it’s a high-end home, a modern office, or a commercial property, we deliver projects that elevate both form and function. By seamlessly blending design innovation with practical solutions, we ensure every project not only enhances the aesthetic appeal of a space but also maximises its value and usability. At CM Loft Conversions, we are passionate about creating bespoke spaces that reflect the unique needs of our clients. From concept to completion, we focus on the fine details and provide a smooth, stress-free experience. Whether you’re looking to transform your home, expand your business premises, or refurbish a commercial unit, our team is committed to delivering results that exceed expectations.
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Latest review:
I met Charlie and his team from CM Builders Ltd when they were completing a loft extension and ground floor extension for one of my neighbours. Quotation and budget I was given an estimate subject to drawings as I was on a strict budget that I had to keep to for the build. Charlie was able to help me keep to the budget, both at the final agreed plan and during the build. The project was complex in that whilst it was a loft extension, all of the house was rebuilt. The only thing kept was the external walls and first floor rafters. Whilst the footprint of the first floor was not being changed I wanted to bring it up to current building standards with extra insulation. All of the plumbing and electrics were also replaced including a new boiler. The overall build has come in on budget, save for agreed enhancements that I did not think of at the planning stage and or building regulations such as double ceiling fire plaster boards. There were also items such as the original stairs that I wanted to keep, but Charlie was able to increase the height space in the kitchen making the worktop much more usable for tall people for a larger part of the kitchen. These were suggested to me as potential options as part of the build. Stage payments The stage payments have all been sensible throughout the build and linked to the ongoing work schedule. I have not therefore had any concerns in this regard. Quality of work This was a very complicated build as unlike the ground floor the first and new second floor are “L” shaped. The new 2nd floor included an en-suite and 2 bedrooms. Overall the house has been increased from 2 bedrooms 1 bathroom, to four doubles and 2 bathrooms. The quality of work is excellent and Charlie project manages his team to ensure that they all deliver to a high standard- if it is not done correctlt they do it again, with Charlie spotting any issues. Timeline of build This has generally gone to plan very well. As with any build you have to be realistic as things will happen outside of anyone’s control. When issues have arisen Charlie manages them to a conclusion. Also be realistic if you are having to manage to a tight budget. I had to plan for various stage receipts of cash before I could order the kitchen and bathroom items - make sure you understand how this impacts the build and availability of the work force, recognising that CM Builders have to book kitchen fitters and plumbers. CM Builders are also very helpful in that they have sorted out issues with the brick work of my freestanding garage (nothing to do with the build) and also a neighbour’s wall that could have been dangerous to the public, should it have failed. Conclusion The whole family are very pleased with the outcome and we now have the equivalent of a brand new house that has been built to a very high standard. This has definitely been worth doing both from a valuation perspective and quality of life perspective. I would not hesitate to instruct Charlie and his team again.
Sorin Dobrila
Rating: 5 out of 5
Extension Builder in Belsize
I've been in trade all my life, and most of the time engaged in: 1. Property Renovations and Remodellings – involving extensions, conversions, repairs and refurbishment works on residential properties. 2. Small/middle size commercial projects – involving repairs and refurbishment works for commercial clients.
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Latest review:
Extensions- 25 Aug 2021
Having had bad experiences in the past with other builders, this time we tried to do our homework properly before hiring someone. We couldn't have chosen a more competent and professional builder! We obviously asked around and had many quotes (some ridiculously expensive, others didn't even seem to understand what we wanted to do) but Sorin immediately impressed me with his detailed and fair quote, knowledge and lots of suggestions (he's the kind of guy that immediately gives you the impression that he knows what he's talking about). We encountered some issues during the works (which is to be expected if you didn't build the place yourself) but Sorin and his team did an amazing job and always gave us regular updates. End result? Work completed on time and a new construction that is exactly what we asked for (plus other things here and there that he kindly sorted while he was on site!)
Ioan Hrit
Rating: 5 out of 5
Extension Builder in Belsize
With over 13 years experience I'm confident in all aspects of groundworks including new build and extensions from footings up to damp course, drainage and the slab construction, kerb laying, block paving; drives paths, slab laying, septic tank installation and soakaways.
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Latest review:
Groundwork & Foundations- 31 Oct 2025
Fantastic all round service. Ioan is very hard working, very knowledgeable in his field and is very well organised and experienced with the logistics and execution of all types of groundworks. I would highly recommend.
A. plastering
Rating: 5 out of 5
Extension Builder in Belsize
Hi. My name is Fatos. I have been in construction for over 17 years. We undertake rendering, plastering and painting jobs. High standard finish in very competitive prices. We also do loft conversion,roofing, plumbing, electric, tiling, extension ect. Our prioritie is to get the job done in very high quality
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Latest review:
Plastering- 22 Oct 2024
We needed to plaster our house ASAP and Fatos completed it in a short time. The house looks amazing, he was quick, efficient and was a great communicator. I would highly recommend him.
AJ REFURB SPECIALIST LTD
Rating: 5 out of 5
Extension Builder in Belsize
With over 20 years of experience in the building industry, we have honed our skills to handle projects of all sizes. Our commitment to quality and craftsmanship ensures that every job is completed to the highest standards,
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Latest review:
Bathroom Fitting- 21 Jun 2025
Great company, attention to detail & Joe went over & above. I would recommend them highly. Thanks for such an awesome renovation, hope to do future projects with you 😊
W&T Building Maintenance LTD
Rating: 5 out of 5
Extension Builder in Belsize
WT Construction Service LTD. has been in business since 2002 and we`re specialists in design, planning, structural, building service, house extensions, loft conversions, joinery and renovation work covering whole of London.We guaranteed high quality finish on competitive price. We`re signed FMB,TRUSTMARK
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Latest review:
William and his company fitted a new kitchen for me and did the painting and wallpapering as well. They did a professional high quality job within a short time. I was absolutely satisfied with their service and their prices. They work fast, clear and precisely. I would highly recommend them to anyone.
SIXTHART LTD
Rating: 5 out of 5
Extension Builder in Belsize
We are an Architectural and Interior Design Studio. We effective planning and technical drawing services. Our Services - Site Survey -All Drawings with Cad Software (Demolish/Proposed) - Draft Planning - Pre Advice Planning - New Build Design - Loft Conversion - Home Extensions - 3D Visulation -Kitchen &Bathroom design projects - Preparation and submission of planning applications - Hourly\Daily Based CAD Services - 3D Modelling (Internal & External Visualisation) -Member of TAG (Traditional Architecture Group) -Bachelor’s Architectural Design Practice -NAAB -TMMOB
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Latest review:
Extensions- 16 Sep 2024
Erhan was excellent. He followed my project from start to finish and kept me updated throughout. Here to the next project!
H&M Construction
Rating: 5 out of 5
Extension Builder in Belsize
We do carpentry and roofing works. We present our work professionally. We strive to please the customer. We have experience over the years. Our prices compete with everyone. Our headquarters is in London
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Latest review:
Carpentry- 27 Mar 2022
We were very happy with Hesham’s work on a tricky job mending our Victorian window shutters.
W8 Build Ltd
Rating: 5 out of 5
Extension Builder in Belsize
Hi, I’m Jon, the Founder of W8 Build. With over three decades of experience in both modern and listed buildings, I’ve dedicated my career to transforming spaces – from bespoke home extensions and loft conversions to the careful restoration of historic landmarks. I even had the honour of working on Windsor Castle alongside Her Majesty The Queen after the 1992 fire, a project that taught me how to balance grandeur with precision. At W8 Build, we believe exceptional craftsmanship should be accessible. Grounded in values of integrity, reliability, and meticulous attention to detail, my team and I bring the high standards of historic restoration to every project – all at market-competitive rates. Whether you’re seeking a stylish roof terrace, a complex basement conversion, or a heritage-sensitive renovation, you’ll receive a fixed-price, transparent proposal and a commitment to excellence that makes quality affordable. There are no hidden fees or inflated costs here – just clear communication, thoughtful planning, and the peace of mind that comes from working with a team that treats every project, whether a royal landmark or your family home, with equal care and professionalism. Let’s work together to bring your vision to life, blending timeless quality with modern practicality. Your dream space deserves nothing less. W8 Build by Jon Taylor
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Latest review:
Extensions- 14 May 2025
Jon was able to take a failed project from a previous contractor and manage historic building preservation, regulation in Westminster, a lack of parking, plumbing from the Victorian age, and a demanding client to deliver a beautiful result. I love my garden flat extension, it manages to respect the historic nature of a building from the 1840s while also adding amenities to be proud of in 2025. Thank you Jon (and team) and best of luck with future business.
GNG Building Services
Rating: 4.8 out of 5
Extension Builder in Belsize
With our extensive experience in home improvements, refurbishments, and building work, no job is too small or large. We've helped countless homeowners across our local area with creating their dream home. Get in touch today to see how we can help you. In case just a single room refurbishment isn't enough and you want to renovate your entire home then look no further than GNG Building Services Ltd. We have the skills to renovating your home a breeze!!!
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Latest review:
Hard Flooring- 21 Sep 2021
Very pleased with the service provided by Nick . Our hard wood flooring in dining area was badly damaged but it was replaced and restored very professionally to its original glory. He is very nice, polite person and very easy to communicate. He is an excellent carpenter and if needed I will use his service again.
AlfredM Building Contractors Ltd
Rating: 5 out of 5
Extension Builder in Belsize
AlfredM Building Contractors LTD Construction company specialising in • Loft Conversions • Extensions • Full House Refurbishments • Domestic & Commercial Building Services • New Build Eager to bring your dream project to life. Dedicated, efficient and passionate.
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Latest review:
Carpentry- 18 Jan 2025
Alfred and his team have done a great job. Replaced the floorboards, joists, installed insulation and damp proofing and sent the extra mile. Highly recommended and I am already using them for a host of other work.
Florin Pascu
Rating: 5 out of 5
Extension Builder in Belsize
Hello, I'm florin and welcome to my profile! I've been working in construction and building for the past 15 years, and have made all my customers happy, completing work to a high standard very efficiently. I'm available to talk anytime if you are interested to take a hard working person like me. Don't hesitate to contact!
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Latest review:
Plastering- 15 Dec 2025
Excellent. Definitely asking Florin to come back for the next two rooms.
NA
Rating: 5 out of 5
Extension Builder in Belsize
Skilled, tidy bricklayer. Highly competent in building, pointing and restoration. Garden walls, extensions, new builds, etc
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Latest review:
Jack built a brick buttress to structurally support my garden wall. Originally I was going to rebuild the entire wall, but Jack’s advice to build a buttress saved me a lot of money! The job was done quickly, affordably and to a high standard. Would highly recommend.
SEASOUTH BUILDS LIMITED
Rating: 5 out of 5
Extension Builder in Belsize
At Seasouth Builds, we bring over 5 years of hands-on experience in the building and construction industry. Known for our loyalty, reliability, and attention to detail, we take pride in delivering high-quality workmanship on every project
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Latest review:
Tiling- 24 Sep 2025
I hired seasouth builds because not only did he give a really reasonable quote, but he also had knowledge of tiling over retrofit underfloor heating - which other tilers seemed to be really hesitant to work with. The job was done to an excellent standard - he’s a real perfectionist. It did take a bit longer than expected, due to some floor level issues which he didn’t account for when he quoted. I was really worried about the price increasing out of my budget when we started running over time, but I was so grateful to find that he was a really honest guy who stuck to the agreed quote and didn’t try to make it my problem one little bit. He was polite and friendly throughout the whole job, turned up whenever he said he would, and kept in constant contact. Really honest (I happily left him unattended in my property). Customer service was excellent, nothing was too much trouble. 10/10 would recommend.
ScutariConstruction
Rating: 5 out of 5
Extension Builder in Belsize
Scutari Construction is a limited company based in London. We are a very reliable and professional team of tradesmen with over 10 years of experience on the building industry, committed to deliver the highest levels of quality and service to our clients.
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Latest review:
Extensions- 14 Apr 2021
Mel and team completely transformed our house in a very timely and professional manner. I honestly cannot say enough good things about him. The team works really hard and their model provides the fastest, highest quality construction at a reasonable price. Use these guys!

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.