Extension Builders in Welwyn

Name: Extension Builder
Brand: MyBuilder
SKU: extension-builder
Rating: 3.8 (14 reviews)

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Some of our top rated extension builders in Welwyn

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JDL Construction
Rating: 5 out of 5
Extension Builder in Welwyn
JDL Construction Limited are a Hertfordshire based building company offering both domestic and commercial services. We specialise in all aspects of construction including Home Extensions, New Builds, Garage Conversions as well as specialist Brickwork Contractors. Our company is fully insured and our tradesman are all fully qualified. JDL are members of many trade associations including Constructionline, CHAS, Federation of Master Builders and Federation of Small Businesses.
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Latest review:
The project was to construct a 15m2 extension to our rear lounge on the ground floor plus a 4m2 extension to the bathroom on the first floor. This involved foundations, walls and roof tiling in addition to the installation of a 5m long RSJ to support the first floor bedroom. Jamie was selected because of his recent training and apparent enthusiasm. He planned and carried out the work very well. Problems when encountered were discussed and resolved with professionalism and enthusiasm. The resulting work has been completed to a high standard and I am well satisfied with the result. The time taken was as planned, he worked on a daily rate which was to my budget. Jamie' strengths are a good basic knowledge of the building regulations, good communication skills with other workers, suppliers and inspectors and excellent basic brick laying skills with a eye for dimensional regularity and excellent final appearance. I would strongly recommend this young and enthusiastic tradesman for any similar project work involving use of his excellent bricklaying skills.
U & A Builder
Rating: 4.9 out of 5
Extension Builder in Welwyn
We've been ground-workers for over 16 years now and we've got lots of experience. We specialise in many aspects such as groundwork, driveways, landscape gardening, underpinning, paving, foundations, extensions, fencing and general building work. Our jobs have a warranty and also guarantee to complete all jobs to a high standard.
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Latest review:
Landscaping- 19 Mar 2024
Completely professional from start to finish. Urim and Aryam are both excellent communicators, which made a huge difference in planning the drainage for our patio, and rebuilding our front steps. We had every confidence in them from the outset and they fulfilled all our expectations. A great team!
RDP Construction
Rating: 5 out of 5
Extension Builder in Welwyn
Small building company covering all aspects of building specialising in bathroom & kitchen installations , experienced tradesman with a huge knowledge of the building trade with polite free advice given & free quotations. If you require more pictures of my works then drop me an email and I can send them . Regards Mr R D Pulfer
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Latest review:
Bathroom Fitting- 24 Feb 2020
Russell finished our bathroom in high standard. We are so happy that we found him. I trust his work and I would recommend him over and over. Thank you Russell!
My Craft Building Solutions Ltd
Rating: 5 out of 5
Extension Builder in Welwyn
My Craft Building Solutions Limited are a family run business, and we offer all aspects of building services. No job too big or too small with a lot of our work done for Anglian home improvements we understand the importance of customer care We specialise in: Extensions Conversions Porches Bricklaying
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Latest review:
Groundwork & Foundations- 27 Sep 2023
A team of 3 bothers, nice guys and did a good job. maybe a little over priced but I did agree the price before, so really I cannot complain.
UK NAMA Constructions Ltd
Rating: 5 out of 5
Extension Builder in Welwyn
Garden Fencing, Garden Decking, Artificial Grass, Wooden Floor Laminating, Decorating, Partitions.
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Latest review:
Carpentry- 28 Jan 2026
Ali did an exceptional job designing and building our staircase, and I couldn’t be happier with the result. From start to finish, he was a complete gentleman — polite, respectful, and a pleasure to deal with. Ali is clearly a true specialist at what he does. His knowledge, attention to detail, and confidence in his craft really stood out. He was able to design and install the entire staircase in just one day, which was genuinely impressive given the quality of the finish. He worked efficiently, kept the area tidy, and took great pride in his work. It’s rare to find someone who combines skill, professionalism, and good nature so well. I would highly recommend Ali to anyone looking for a high-quality staircase installed by a true expert.
Hatch Building & Construction LTD
Rating: 5 out of 5
Extension Builder in Welwyn
Hatch Building & Construction are a local family run business who take pride in their reputation, delivering a high standard of work and completion on all projects. We offer a full design service for all our projects incorporating architects, structural engineers and designers, this means we can offer a full in house service from conception through planning, building control and conservation. We are a member of the FMB where you can find testimonials from previous customers.
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Latest review:
Extensions- 10 Jul 2019
The initial reason we chose Hatch Construction to start is down to Lee.......... Text missing Cleanliness – Not only I have commented, but each of my neighbours who are all elderly were very complimentary about how the team worked and how clean the site was. I was very happy that my patio and garden were all left intact. Staff – A great team, knowledgeable, friendly and flipping hard workers. Nothing was ever a chore for them and they were happy to share their knowledge and experience. An overall lovely group of blokes. Quality of Work – The workmanship was spot on, even with a knowledgeable family member at hand to oversee some of the build, he was more than happy with the workmanship demonstrated by the guys. Been in the house a month or so now and all appears to be as it should be. Knowledge of Suppliers – The Company has links to many reputable companies in the area to put you in contact with, we used all that were recommended to us and we couldn’t better the price and service anywhere else without dipping on quality. Flexibility – A very flexible team, whether time constraints or having to work around certain events, Lee will aim to make it as plain sailing as possible, given that having building work is such an upheaval. Overall I would recommend Hatch Construction to anyone, they are an honest firm and will do their best on the job in order to meet your expectations. I am more than happy with my new house and love what they have done to transform it
Milestone Brickwork
Rating: 5 out of 5
Extension Builder in Welwyn
Local bricklayer based in herts and Essex, we also undertake patios and fences.
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Latest review:
Jack came and quoted to lay a new patio and a shed base. He listened to exactly what I wanted (something other workmen didn’t do!) and came back with a very reasonable quote and said he would complete the job on a weekend as I wanted it done asap. From start to finish Jack was really polite and friendly and worked really hard to get the job finished - so much so, I’m adding more bits to the garden and will get Jack back over to do it!
Smart Constructors Ltd
Rating: 5 out of 5
Extension Builder in Welwyn
We represent a new construction company with many fields of activity, such as meintenance, cleaning, extensions a.s.o. We are more than happy to tackle any chalange.
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Latest review:
Handyman- 9 Aug 2019
Very happy, good (fair not cheap) price. Adrian contacted me, arranged to come quite quickly, efficient and completed the job in good time... left site nice and tidy. Would recommend 😀 Thanks Adrian
DJ Cox Building Services Ltd
No reviews yet
Extension Builder in Welwyn
All building work, extensions, loft conversions, electrics, plumbing, plastering, bricklaying, patios, drives, bathroom & kitchen fitting, fencing.
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P Jordan and Sons Ltd
Rating: 5 out of 5
Extension Builder in Welwyn
Jordan & Sons are a family run business with over 30 years experience specialising in extensions, new builds, all types of groundwork, drainage, brickwork, driveways, patios, resin bound & block paving. The work we carry out is second to none, finished to a high standard while providing an excellent service. We own our own plant with relevant tickets, & we take on all commercial and domestic projects.
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Latest review:
Extensions- 10 Mar 2025
Hired paul to carry out works to open up my rear wall and install a new RSJ steel beam for a bifold door. From day one paul helped me out with some issues i was having with my structural engineer design, priced up the works which was very competitive with other builders and While having a visit before works started, i asked paul if he could do some extra works (installation of plasterboard walls and plastering) which he was happy to do. Todd then started works within a few days. Now all the works are finished and im very happy with the finished product. Paul and Todd were brilliant and would happily recommend them to people if they need any works done. I will be using them again in the future.
ELITE UPGRADE SOLUTIONS
Rating: 5 out of 5
Extension Builder in Welwyn
With two decades of hands-on experience, I bring a wealth of expertise to every home improvement, maintenance, and handyman job. As a solo trader, I offer a personalized approach, ensuring each project receives the attention and care it deserves. From indoor renovations to outdoor garden buildings, I am proficient in a range of skills, delivering high-quality results that exceed expectations. Trust me to enhance your living space with precision and dedication, backed by 20 years of proven craftsmanship.
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Latest review:
Handyman- 28 Oct 2024
Martin was responsible, punctual, and good at what he does. He explains things well and the communication was great, considering that I have been remotely managing this project, never on site! Will use again.
Kev home improvement
Rating: 5 out of 5
Extension Builder in Welwyn
15+ years of building experience ! We are new on MyBuilder Garden design Paving, Driveway specialist Foundation Porch Extension General building Complete refurb
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Latest review:
Landscaping- 24 Jun 2025
Razvan and his team were incredible! Really polite, lovely guys. Kept the site clean and tidy. Did an incredible job - absolutely in love with our new patio!! Cannot recommend enough!
Philip J Pulzer
Rating: 4.7 out of 5
Extension Builder in Welwyn
As a design and build contractor, we will produce drawing for both planning approval and building regulation. We will then provide a detailed estimate of building costs. If we do win the building co tract then all architectural design cost will be free of charge.
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Latest review:
Extensions- 11 Feb 2019
Completed job on expected timeline and assisted when challenges came up
Lewis property maintenance ltd
No reviews yet
Extension Builder in Welwyn
Over 15 years experience in all different variations of construction, exclusive new builds to refurbs on 1 bedroom flats. No job to big or small
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OFIX Ltd
Rating: 5 out of 5
Extension Builder in Welwyn
With over 34 years experience I offer a complete design and build package as well as providing specific services for smaller contracts. I have been vetted by the Federation of Master Builders and strive to provide excellence. I am an extremely competent multi trader with a good eye for detail. With a team of experienced subcontractors I will deliver incredible quality installations on time within budget.
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Latest review:
Carpentry- 8 Mar 2025
Absolutely over the moon with Mike, he did a fabulous job. Would definitely recommend him!
Hunbuild Ltd
Rating: 5 out of 5
Extension Builder in Welwyn
With over 25 years of experience in construction Open Plan Solutions is regarded as one of the most successful companies based in St. Albans and the surrounding counties working on both private and commercial property development. Open Plan Solutions provides a successful track record within a safe environment for the community it works in. Our speciality in providing construction needs makes us the first choice amongst customers looking for quality services. We strive to deliver all construction on time and to budget – and we consistently do, which is why our client base has continued to grow and we consider ourselves to be the number one building and construction experts covering St. Albans, Hertfordshire and surrounding areas.
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Latest review:
Restoration & Refurbishment- 20 May 2026
Excellent service from a very professional team. They removed two chimney breasts for us, turned up right on time, and finished the work to a very good standard. They also did a great job of protecting the house from dust while working. We are very happy with the final result and would definitely recommend them.

3.8

Top rated Extension Builders

Our Extension Builders in Welwyn, are rated 3.8 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.