Extension Builders in Welwyn

Name: Extension Builder
Brand: MyBuilder
SKU: extension-builder
Rating: 3.7 (13 reviews)

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Some of our top rated extension builders in Welwyn

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Ava Constructions & Decors
Rating: 4.9 out of 5
Extension Builder in Welwyn
Ava Constructions & Decors Ltd is a UK-based construction and renovation company committed to delivering top-quality craftsmanship and reliable project management. We specialise in full refurbishments, extensions, bathroom and kitchen installations, and commercial fit-outs — always tailored to the client’s vision and delivered to the highest UK building standards. With a keen focus on transparency, timelines, and customer satisfaction, Ava Constructions has earned the trust of homeowners, investors, and developers alike. Punctuality and completion of work on time are a priority .Our team always respect the client wishes and work with them to achieve the best possible results to their satisfaction. Thank you in advance
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Latest review:
Extensions- 16 Apr 2026
I would not recommend this builder based on my experience. Instead of using crushed concrete they used soil to fill the house flooring for underfloor heating. 1 The project suffered from poor communication, repeated delays, and a lack of clarity around responsibilities. There were serious issues with the foundation works, which failed Building Control inspection and now require remedial engineering input before works can proceed. The site was also left incomplete and not in an acceptable condition. Despite substantial payments being made, key documentation, technical responses, and follow-through were lacking, leaving me to resolve major compliance and structural issues independently. My experience has resulted in delay, additional cost, and considerable stress. I would strongly advise others to ensure there is a detailed written contract, clear scope of works, and defined accountability
Fastway Constructions Limited
Rating: 5 out of 5
Extension Builder in Welwyn
At Fastway Constructions, we are dedicated to redefining the construction industry through sustainable practices and innovative solutions. Based in the United Kingdom, we pride ourselves on delivering exceptional quality and reliability across four key sectors: Residential Constructions, Commercial Constructions, Industrial Constructions, and Renovation & Remodelling Here at Fastway all of our employees are fully qualified, skilled and very experienced building contractors that have worked on hundreds of projects over the years resulting in 100% client satisfaction, full job completion on time, and always well within budget. All employees hold cscs cards for their relevant trades along with health and safety certificates and first aid for a competent safe worksite at all times. We are a building contractor with a professional approach to all our projects. We offer a seamless and multi-trade service, for all domestic projects from new builds, extensions, loft conversion, renovation to fully finished houses, all tailored to meet our clients’ specific requirements.
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Latest review:
Plumbing- 1 Aug 2025
Jitin did a good job in finding a solution to the leak in the washing machine drainage pipe. He used his experience in problem solving and fixed the issue. Thanks Jitin
Jaspal
Rating: 5 out of 5
Extension Builder in Welwyn
Hi,i work very well and im very carefull about thier work.
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Latest review:
Plastering- 3 Aug 2022
Very good job and kept tidy, would recommend.
Til construction LTD
Rating: 5 out of 5
Extension Builder in Welwyn
TIL Construction LTD is a well-establish company that provides a complete and cost-effective solution for your building needs. We pride ourselves on a team of highly skilled craftsmen and professionals ready to deliver any sized construction project from start to finish. Whether it’s a new build, extension, loft conversion, or renovation, we can help with a portfolio of building work across London and other cities within the UK.
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Latest review:
Carpentry- 5 Aug 2023
A gréât expérience. Thé team were very professional, well priced, and did a great job. They left our apartment immaculately clean and fixed all issues we had. They were extremely polite and responsive and did a great job in the timeframe and for the quoted cost. Highly recommend
ALBERTHALL CONSTRUCTION LTD
Rating: 4.7 out of 5
Extension Builder in Welwyn
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.
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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!
Earthmates Construction Limited
Rating: 5 out of 5
Extension Builder in Welwyn
Introducing Earthmates: Your trusted partner for all property needs. We offer comprehensive services in new builds, extensions, landscaping, fencing, loft conversions, and complete property management. Whether you’re planning to build from the ground up, expand your existing space, or enhance your outdoor area, Earthmates delivers expert craftsmanship and tailored solutions to transform your property vision into reality. Let us help you create, renovate, and manage with quality and care at every step.
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Latest review:
Landscaping- 20 Sep 2025
Earthmates absolutely transformed my garden. They did an amazing job so I hired them again to redo my driveway. I would definitely recommend them an would hire them again an again. They were a good bunch of guys friendly and professional. If you want a job done right hire Earthmates Construction!
Your Space
No reviews yet
Extension Builder in Welwyn
We create the perfect space you require. You choose, we build. We can assist, from design, all the way to the finished article. All aspects of buildings works are carried out.
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Relied on builders ltd
No reviews yet
Extension Builder in Welwyn
Hello my name is Costel I have experience in brickwork more then 10 years I have very good reference from customers and proves with photos if you wish to see I Olson have my own company and a van whith tools I have more skills with paving stones etc. And gardening walls and driveway I’m responsible for my work to be everything done..thank you
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Am@ contractor
No reviews yet
Extension Builder in Welwyn
I will like to make my one customers
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Mat al construction LTD
No reviews yet
Extension Builder in Welwyn
Ground worker with many projects finished, hard worker ready to take on new projects, ,trusted and experienced ,quality , fast, and safe. All ways looking forward
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All Quality Construction
New on MyBuilder
Extension Builder in Welwyn
With over 20 years of hands-on experience in building lofts and extensions, we specialise in delivering reliable, high-quality home construction across Essex, Hertfordshire, and North & East London. Our focus is simple: quality work, clear communication, and customer care you can depend on.
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Madalin Alin
No reviews yet
Extension Builder in Welwyn
If you need a good team for any jobs dont hesitate to call us!
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Param group
No reviews yet
Extension Builder in Welwyn
Hi, Here we are satisfy you by our work and quality thanks
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Codenra ltd
No reviews yet
Extension Builder in Welwyn
I carry out general building work such as loft conversion, home extenstion , partition , plastering , laminate and tail.
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SHIVAY DEVELOPMENTS LTD
Rating: 5 out of 5
Extension Builder in Welwyn
From Concepts to Creations, Shivay Developments Ltd has combined experience of over 15 years in Construction trade. Our team consist Expert Tradesmen and Experienced Project Managers with a single point of responsibility and accountability throughout the construction process.
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Latest review:
Extensions- 3 Jun 2020
Mohit and his team at Shivay Developments completed extensive improvement work in my house (rear extension, internal structural work, kitchen, toilet, boiler installation, plumbing and electricals, flooring & finishing). The end result exceeded all my expectations in terms of cost, time and quality making me a very happy man. Sharing some pictures would have done proper justice but unfortunately there doesn’t seem to be a way to upload pictures with the feedback. In spite of living inside the property whilst the works were ongoing, we hardly felt any impact owing to how well Mohit had planned the whole thing and the advance notices he used to give us from time to time. All the guys too were very considerate when it came to minimizing the inconvenience all the dust and noise could cause to us and also the neighbours. I also liked the fact that nothing was rushed and a great deal was given to attention for details and the result was just splendid. I guess at the end of the day, it’s what you see that matters most. However amongst everything that hit the right notes for me during the entire process, it was the confidence that I can trust this team to do the job right stood out. It was a bunch of warm and friendly people who had direction and knew what they were doing. A special mention and a big thank you to Kash and Pala to lead the work from the ground up and Mohit for taking up and managing the job and of course for the celebratory rounds of beers :) Do keep in touch
Kamboj Multisolution Ltd
No reviews yet
Extension Builder in Welwyn
KAMBOJ MULTISOLUTION LTD We are Professional builders, working on Projects mainly connected with Residential areas. We practice plentiful Construction areas such as LOFT CONVERSION EXTENSIONS BATHROOM (FULL FITTINGS ) PAINT ALL TYPE FLOORING (INCLUDE TILES AND CARPET) PATIO SLABS DRIVE WAYS CONCRETE WORKS and Many More Please do not hesitate to get free Quotes and visits ARSHDEEP SINGH
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3.7

Top rated Extension Builders

Our Extension Builders in Welwyn, are rated 3.7 out of 5 based on 13 reviews from customers like you.

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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 Welwyn?

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

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

What are the hourly rates of extension builders in Welwyn?

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

Find extension builders in Welwyn with MyBuilder

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

Step 2: Compare different extension builders in Welwyn

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

Step 3: Hire Welwyn extension builders with confidence

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

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

What to ask a Welwyn extension builder before hiring?

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

An extension builder in Welwyn 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 Welwyn 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 Welwyn?

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 Welwyn 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 Welwyn 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 Welwyn

Can an extension builder in Welwyn help with planning permission?

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

Many Welwyn 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 Welwyn help with materials and finishes?

Yes, most extension builders in Welwyn 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.