Extension builders in Welwyn

Name: Extension Builder
Brand: MyBuilder
SKU: extension-builder
Rating: 4.7 (14 reviews)

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Some of our top rated extension builders in Welwyn

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Lee Construction Builders LTD
Rating: 5 out of 5
Extension Builder in Welwyn
Lee Construction Builders LTD are your local Builders in Stevenage. We offer free quotations and can build your project for a fixed price. All our team are fully qualified and experienced tradesmen that have seen and dealt with every building challenge possible. We have a track record of happy satisfied customers as we provide a friendly, professional service, and are always respectful of our customers, understanding that our workplace is your home.
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Latest review:
Roofing (Pitched)- 17 Apr 2016
Fantastic job; quick reply; thorough professional job. Lee really likes doing the job right; certainly not a cowboy. He really took his time in assessing the problem. Very neat job from the inside and out. Highly recommended.
Craft Property Solutions Ltd
Rating: 5 out of 5
Extension Builder in Welwyn
Craft Property Solutions is a leading property refurbishment and remodelling company that specialises in both the residential and commercial sectors. Our team of experts can carry out interior alterations, extensions, loft extensions, and office fit-outs. We also have a specialist tiling division that can handle all your tiling needs.
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Latest review:
Bathroom replacement. Team were very efficient and made additional effort to accommodate the tenants. Communication was great throughout.
DRJ Homeimprovements
Rating: 4.9 out of 5
Extension Builder in Welwyn
DRJ Home Improvements Ltd provides reliable and trustworthy service completed to a high level of standards because I believe you don't need to move, Just improve. I have got 20 years experience in the building trade satisfying clients. We are a team that will get your job done from start to completion.
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Latest review:
Extensions- 31 Jul 2026
Dan, is an immense organiser, everything on site runs like clockwork. He’s neat and tidy, and cleans up daily. The tradesmen he hires are top notch and all love working with him. The job is well thought out from start to finish and he considers your needs throughout as well. For example we had a kitchen extension and he made sure at the end of each day we had running water and a hob! Very courteous. He keeps you well informed of what’s going on day to day, and presents exemplary work before the building inspector. Lee, his right hand man, is equally as thorough and they make a wonderful team. Every aspect of the build is well thought out. All of the materials arrive on time. Tradesmen are booked in advance and are always punctual. Our build ran like clockwork. We had progress chats every evening on the phone and the plan for the days ahead. Dan likes to keep you well informed of everything going on, and will give expert advice on any snags throughout. Would 100% recommend him.
Ervis
Rating: 5 out of 5
Extension Builder in Welwyn
I’m a reliable and skilled handyman with several years of experience in the construction industry. I specialise in carpentry, joinery, hard flooring, and a wide range of general home repairs and maintenance. I take pride in delivering high-quality workmanship, completing every job to a professional standard and exactly to my clients’ requirements. I’m always happy to offer honest advice and practical solutions to help you get the best results for your project. Whether it’s assembling furniture, fitting doors, installing flooring, repairing woodwork, or tackling general handyman tasks, I’m committed to providing a dependable, friendly, and competitively priced service. Customer satisfaction is my top priority, and I always leave every job clean, tidy, and completed to the highest standard.
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Latest review:
Handyman- 20 Sep 2026
Ervis has just finished constructing a Dunster House 6x4 shed in my garden. His communication was excellent, as was his punctuality. I was really impressed with his work ethic and his craftsmanship - as it was not a simple shed to construct. Really happy with the end product. Would 100% use again for any jobs on my house! Thanks Ervis!
James Harris
Rating: 5 out of 5
Extension Builder in Welwyn
We are a small team that has been in the industry for 28 years, working on large and small domestic and commercial contracts . We cover all domestic building works from extensions ,loft conversions and renovations and we have a large portfolio of our works and client feed back . We pride ourselves on -quality work - in-depth knowledge of the building industry ,modern building practices and building regulations Ensuring your project meets the highest of standards
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Latest review:
Extensions- 13 Jul 2026
James did a brilliant job on our kitchen renovation and extension. He was on site every single day, which made a huge difference to how smoothly the project ran. Communication was excellent throughout: he explained what was happening at each stage, flagged issues before they became problems, and was always straightforward to reach. What stood out most was how honest and trustworthy he was. No corners cut, no unnecessary upselling, just solid, reliable work from start to finish. The fitting itself was done to a high standard and the whole extension came together exactly as we’d hoped. Would recommend James without hesitation and wouldn’t hesitate to use him again.
Newell groundworks ltd
Rating: 5 out of 5
Extension Builder in Welwyn
A small family run business with over 20 years experience.
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Latest review:
Groundwork & Foundations- 15 Oct 2025
Stuart was great to work with. Knowledgeable, hardworking and committed to doing a great job. We will be using his services again in the future.
Design A View Limited
Rating: 5 out of 5
Extension Builder in Welwyn
At Design A View we specialise in window and door installations, porch builds, conversions, structural alterations for new bifolds or sliders. We are Fensa and CPA registered offering insurance backed guarantee’s With 30 years experience in the industry we offer a wide range of quality products and a finish of work that sets us apart, creating new openings and improving existing. Products: We are proud to be an approved Origin supplier Also Cortizo Aluminium doors, sliding and bifold Standard U-Pvc, flush casement windows, vertical sliding windows and doors Wooden vertical sash, casements and doors We look forward to working with you
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Latest review:
Extensions- 21 Oct 2025
Quick, honest pricing and great advice to minimise the impact rather than trying to inflate it like other traders do. I would highly recommend Lee and his team.
Bathroom fitter,Handyman,Plumber,Electrician
Rating: 5 out of 5
Extension Builder in Welwyn
We are a small team of multiskilled traders,specialised in kitchen and bathroom refurbishment as well as any other building work Reliable,tidy and reasonable priced who takes pride in their work Thank you
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Latest review:
Painting & Decorating- 24 Aug 2026
Daniel and the team did an amazing job fully decorating and transforming our home, it’s exactly how we’d imagined. Someone turned up each day even during the peak summer period - they were always reliable, very polite and hard working. I would highly recommend!
D & C Kitchen Installations Limited
Rating: 5 out of 5
Extension Builder in Welwyn
We undertake full or part refurbishment or existing and new build works. We specialise in kitchen installations and building alterations. We can provide a full team of specialist to complete all building works from design to completion. We are a registered Ltd company, fully insured and members of BiKBBi and only use registered contractors.
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Latest review:
Ciaran ripped out my old kitchen and installed a new one and at the same time adding a door to the garage. Ciaran’s workmanship is second to none, his eye for detail and knowledge is awesome. Ciaran is a true very polite and all together a sound tradesmen. Always here early and put in the hours. I would absolutely recommend Ciaran and his work it was well worth the wait. Thank you.
T & J Services
Rating: 5 out of 5
Extension Builder in Welwyn
T & J Services are experienced construction and demolition specialists. We specialise in the following: •General Building •Extensions •Conversions •Demolition •Strip Outs •Driveways •Landscaping •Groundwork
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Latest review:
Demolition- 31 Oct 2025
Came on time & supplied a reasonable price. Started the job in good time & when additional work was needed, gave a very competitive additional sum. Completed in good time. A good job was done. Well definitely consider them for any other work & have recommended them to a friend.
B W Brickwork
Rating: 5 out of 5
Extension Builder in Welwyn
I have been established for over 30 years we carry out most building work and paving and driveways we also specialise in brickwork to a high standard
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Latest review:
Landscaping- 24 Jul 2019
Excellent work, really pleased with the finish of our new patio and lawn area. Work carried out quickly and a very reasonable price. Left clean and tidy every day and would highly recommend these lovely chaps
Jgs carpentry
Rating: 5 out of 5
Extension Builder in Welwyn
Jgs carpentry & building services. We are hardworking, trustworthy carpentry and building company based in Hoddesdon. With 20 years experience in the building trade doing anything from hanging a few doors to loft conversions and extensions
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Latest review:
Carpentry- 23 Nov 2019
We had 7 new internal doors fitted. Really great job, very pleased. Would highly recommend.
Nick's Authentic Carpentry and Building
Rating: 5 out of 5
Extension Builder in Welwyn
We're a new company but have the experience and knowledge of any other company.We're professional, organised, and give our customers what they expect and deserve. Being proud workers and undertaking everything thats thrown at us, Our focus is the job we're on!
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Latest review:
Carpentry- 31 Aug 2011
Highly recommended and friendly carpenter. The job was done within 24 hours of posting. He gave me a time and even called to say he was on his way. Price was very reasonable indeed. Job was done to my total satisfaction with 100% professionalism. I am certainly going to have Nick do any other jobs that arise. He clearly has a vast knowledge of a whole range of trades and skills apart from carpentry. It is so nice to have found such an able tradesman who can be trusted to do a great job.
PS Brick Block &Home Improvement LTD
Rating: 4.7 out of 5
Extension Builder in Welwyn
All type of building works to high standards. - extensions - lofts - plumbing - electric - decorating - new build - patios - driveways
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Latest review:
Extensions- 4 Nov 2023
Overall me and my husband are very satisfied with the workmanship and with the final result of our my fake cladded garage door with the new aluminium framed window. The original garage was converted into a habitable room 7 years ago with only a rooflight to bring light into the room, which is now my husband's office and this new window will make a lot of difference therefore we are very happy with the finished work. The work was done very quickly, the builders turned up on time and they were very efficient and helpful, they took particular care when installing the composite slatted panels to the marine plywood. The main contractor Pawel Speiwak also came on site to inspect the works during construction. The quote was also very competetive, a good value for money. I would definetely use them again for any future work in my house and recommend them to other people.
LandMarx Ltd
Rating: 5 out of 5
Extension Builder in Welwyn
Small friendly family run business with over 30 years construction and refurbishment experience. We offer all types of building services wether it is a small maintenance job to a new build . We work on commercial and residential buildings. We also provide project management for self-builders who want to keep to a budget and have someone with the expertise to guide them through the building process from conception to finish. We are CHAS accredited and DBS checked.
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Latest review:
Keith has helped design and fit our kitchen/utility room. Has re felted the flat roof on my garage and extension. He is currently fitting all my doors, skirtings and door linings. He boarded up and plastered doors where we have removed cupboards and larders. Great job, very reliable and multi trade so i would highly recommend him. I'm an electrician so work with a lot of builders so i can recognise a good workman.
ABL Building & plumbing solutions
Rating: 5 out of 5
Extension Builder in Welwyn
We are a family run business, take pride in our work we carry out. We cover all aspects of building works from hanging a door to a complete new build house.
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Latest review:
Plumbing- 28 Jun 2023
Alan was a total professional, clean and tidy, fabulous job, will use him again and recommend him to everyone I know. Top professional.

4.7

Top rated Extension Builders

Our Extension Builders in Welwyn, are rated 4.7 out of 5 based on 14 reviews from customers like you.

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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.