Extension Builders in Welwyn

Name: Extension Builder
Brand: MyBuilder
SKU: extension-builder
Rating: 3.9 (16 reviews)

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Some of our top rated extension builders in Welwyn

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Construction
Rating: 1 out of 5
Extension Builder in Welwyn
We do all construction work Skim ,paint ,wood floor , floor tiles ,krainder Bathroom ,new extension and garage Brick nd block work
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Latest review:
Bricklaying- 11 Mar 2023
The builder came to build a single skim brick wall to the side entrance of my house -: around 120 bricks. He agreed to £300 for labour including inserting a door. Upon arrival, of which he came on foot, he had no tools, no bucket, no drill, no ladder. He had to borrow all of my husbands equipment and sent my husband out for extra materials on two occassions. The lintel he asked us to order was the wrong size, we ordered one that was far too big and wasted more money due to him measuring up the job wrong - again a waste of money. Then, we had to drive him to toolstation to buy a brick cutting tool because of this using our own time and fuel. You would assume a brick layer would have tools if they are doing jobs privately - his colleagues excuse was we are just starting up our private buisness. He then started asking for more money and stormed off leaving all the rubbish behind even though we gave him the £300 as agreed prior to the job. The wall itself is okay but again at one point he refused to build up to the top because of a metal screw apparently impossible to remove, so yet again my husband had to assist with the job and removed the screw. Honestly more hassle than it was worth. Also the door was not fitted so now will need to pay someone else to do the job. I do feel bad for them that do not have any equipment but when you pay money for a job you do expect a certain level of service. I wish them good luck in the future and hope they take this advise on board.
total services
No reviews yet
Extension Builder in Welwyn
WE ARE A FAMILY RUN BUSINESS WHICH HAS BEEN RUNNING FOR 30 YEARS,WE COVER ALL ASPECTS OF THE BUILDING TRADE AND CAN PROVIDE AN EXCELLENT SERVICE FROM START TO FINISH.CAN SUPPLY REFERENCES IF REQUIRED.
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House Renovation Services London LTD
No reviews yet
Extension Builder in Welwyn
I am a London based cont actor with over 10 years experience in property renovation and construction. I specialise in delivering high quality building work, from full refurbishments to extensions and new builds. I pride myself on reliable service, clear communication, and excellent workmanship.
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Top K Construction and Design LTD
No reviews yet
Extension Builder in Welwyn
At Top K Construction and Design LTD, your vision is our project. With over 20 years of experience, we have successfully completed a wide range of projects across London, from new builds and refurbishments to garages and extensions. We are passionate about turning your ideas into reality and prioritize your satisfaction in every step of the process. We love taking on new challenges and working closely with our clients to create spaces that truly meet their needs. Let us bring your dream project to life — quality, reliability, and customer happiness are at the heart of everything we do.
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BMR piling and foundations Ltd
Rating: 4.7 out of 5
Extension Builder in Welwyn
Hi my name is Baden and we specialise in piling and foundations from new builds to under pins no job is to big or to small. We are competitive prices to most other companies.
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Latest review:
Groundwork & Foundations- 3 Aug 2026
BMR has turned my dream self-build into a nightmare. An independent structural engineer has confirmed that the foundations BMR constructed are not in accordance with the approved structural drawings and require remedial structural works before my house can even be built. Defects in BMR's work: 200mm lost from both the front and rear elevations of the approved footprint. Internal load-bearing foundations constructed in the wrong location. Foundation levels between 30mm and 75mm out across the build. Thousands of pounds in remedial engineering, bricklaying and construction costs, plus weeks of delays. The setting-out engineer was appointed and paid by BMR as part of the contract I paid for, yet Baden tried to shift responsibility instead of taking ownership. I gave Baden every opportunity to inspect the site with my contractor and discuss a solution. Instead, he denied liability, refused to discuss the issues any further, and simply walked away from the problem.
A D FOD Construct
No reviews yet
Extension Builder in Welwyn
Hi, my name is Adrian, i am a highly skilled builder. I am reliable, honest and hard working. I don’t waste time and my quotes are competitive. Don’t hesitate to contact me!
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FLYNN properties
Rating: 5 out of 5
Extension Builder in Welwyn
With over 10 years experience and always producing high quality finishes. From kitchens, bathroom to extensions and always with a good positive happy attitude. let us work with you to design and achieve exactly what you’re looking for.
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Latest review:
Tiling- 7 Aug 2023
Paul was great. Easy regular comms. Arrived early on the day and fit me in as best he could. Straight to it, great work, very professional and sorted out some other problems as they were discovered. Talked me through options and did what was asked to a very high finish. Would highly recommend and use again.
Haymore Ltd
No reviews yet
Extension Builder in Welwyn
Built on over a decade of experience across just about every sector of construction, we have the know-how to get your project done. If you're after a loft conversion, rear extension, annex, or even a complete house overhaul, we can do it! Truthfully, almost any builder can do all that, so what makes us stand out from the crowd? We set up Haymore to be different from day 1. Our motto is “Construction Simplified” and we really believe that is what we offer.
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j s brickwork
No reviews yet
Extension Builder in Welwyn
( J S speedybrickwork) Hi it’s brickwork company Can do all sort of brickwork ,block-work ,stone ,masonary My prices are normal and give you best quality of work. Always on time job Just give me a call for any free quotation - Any other building work also undertaken Roofing ,bathroom , painting
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HBO Projects Ltd
No reviews yet
Extension Builder in Welwyn
Here at HBO Projects we believe in quality, technical competence and customer care. We are a construction practice that has access to our own architectural and engineering advisors to ensure that works are always completed to the highest technical competence. Our workforce are time served and well qualified with a history of delivering exceptional work and the experience to ensure projects are well run and managed. We cover extensions, loft conversions and refurbishments.
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Gurwindersingh4ltd
Rating: 4 out of 5
Extension Builder in Welwyn
Hi my name is gurwinder singh I am skilled in plumbing, skimming , roofing , tilling , bathroom fitting , loft, garage conversions . I do jobs at affordable rates. Thanks
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Latest review:
Tiling- 21 Jan 2023
I highly recommend this builder and the team behind it. They have been very professional and efficient in their work, and the results have been outstanding. They have been very accommodating and communicative throughout the entire process, and I have found them to be extremely knowledgeable and helpful. The quality of the work is top-notch and I would not hesitate to recommend them to anyone looking to have a building project completed.
FAIZ Construction LTD
No reviews yet
Extension Builder in Welwyn
FAIZ Construction Ltd is a Gas Safe registered company. We are qualified gas engineers and plumbers with full public liability insurance. Our team of experienced professionals delivers high-quality workmanship, reliable service, and a commitment to getting the job done right first time. Gas services: boiler installation, servicing, repairs, and safety checks. • Plumbing: installations, repairs, bathroom and kitchen plumbing, leak detection. • Emergency call-outs: rapid response for urgent gas or plumbing issues. • Maintenance and upgrades: system improvements, energy-efficient solutions, and compliance work. Gas Safe registered engineers; fully qualified and up to date with regulations. • Public liability insurance for your peace of mind. • Workmanship guarantee — we stand behind the quality of our work and resolve issues promptly. • Professional, hardworking team with years of hands-on experience and dedication. Please feel free to ask any questions or request a free quote. We respond quickly and can provide references and proof of qualifications on request.
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ODG Construction Ltd
No reviews yet
Extension Builder in Welwyn
ODG Construction is engaged in the construction of domestic and commercial buildings. We specialize in groundworks, formwork, reinforcement, and concrete finishing. We promote a safety working environment by following Health and Safety standards. We operate on a 100 miles radius around London Home - ODG Construction Ltd. https://share.google/lQ5BKFPdy1JBhpNso
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We Do Foundations and Extensions Ltd
No reviews yet
Extension Builder in Welwyn
We are actively involved in the provision of top-quality residential and commercial construction services. We expertly coordinate every aspect of our client’s construction project, from design and planning to custom fabrication and on-site management.
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Gur construction ltd
No reviews yet
Extension Builder in Welwyn
Gur construction ltd company is giving less costs as compared to others nd free valuation nd we provide good work
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undercroft construction ltd
Rating: 5 out of 5
Extension Builder in Welwyn
Experienced and dedicated construction professional with over 31 years in the construction industry. I have led and managed teams across multiple high-value projects, including residential and commercial developments, with budgets ranging from £2,000 to £450,000. My expertise covers every phase of the construction process, from initial client contact and planning to project execution and fit-out. Adept at team leadership, scheduling, budgeting, client communication, and health & safety management, I possess a solid understanding of architectural drawings, engineering plans, and construction best practices.
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Latest review:
Groundwork & Foundations- 20 Jun 2025
Excellent work carried out Professionally. Arrived on time 08:15 every morning. Very Friendly and good communication. Will happily be using again.

3.9

Top rated Extension Builders

Our Extension Builders in Welwyn, are rated 3.9 out of 5 based on 16 reviews from customers like you.

Quality screening

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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.