Extension Builders in Welwyn Garden City

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 Garden City

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Felton Home Renovations
No reviews yet
Extension Builder in Welwyn Garden City
Hi my Names Brad We are a New and fast growing company based in Harpenden taking on a variety of work from small carpentry jobs to major Refurbishments/Extensions we only use fully qualified trades and lead by example in the building industry.
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First Class Construction & Glazing Ltd
No reviews yet
Extension Builder in Welwyn Garden City
First Class Construction & Glazing Ltd is a construction and glazing company based in Hertford, providing expert building and glazing services across Hertford and surrounding areas including Ware, Hoddesdon, Broxbourne, Cheshunt, Stevenage & Welwyn Garden City. We specialise in double glazing, window installation, door installation, home improvements, renovations and general construction for residential properties.
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North Builders LTD
Rating: 4.8 out of 5
Extension Builder in Welwyn Garden City
North Builders LTD have a team of specialists which gives you quality and high standard work on Loft conversions, Extensions, Roofing, Renovation, Refurbishment. We based in London and we cover all M25. With the best quality work and proffesional prices on the market we managed to make happy a lot of costumers around London and not only. Our priority is the costumer to be satisfied, the project to finish in timeline and on budget. Contact us for free quotes.
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Latest review:
Loft Conversion- 2 Nov 2025
Full loft conversion with dorma. Blerim always asked the right questions and made really good suggestions. Very helpful and great quality. Would happily recommend him and his team.
Dino design Ltd
Rating: 4.8 out of 5
Extension Builder in Welwyn Garden City
We founded DINO DESIGN out of a pure passion for building. We are two brothers who work together in sync and is a collaboration we're proud off, we construct roofs extensions and loft conversions to an amazing standard which can be seen in the work we do. We like to push boundaries in our field making a project built by DINO DESIGN stand out from the rest. DINO DESIGN is a name you can count on and trust to deliver your project from the paper its drawn on to the material its built from. Explore the rest of our site to learn more about what we offer, and get in touch with any questions. We specialise in: • Single & double-storey extensions • Loft conversions & dormers • Full property refurbishments • Kitchen transformations • Open-plan structural alterations • Landscaping and outdoor works
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Latest review:
Conversions - General- 22 Apr 2026
Had a fantastic experience with Dino Design for an en suite removal. They understood exactly what I wanted and were very responsive throughout, giving me daily updates about how the work was going. So happy with the result- would 100% recommend :)
Grand Improvements Ltd
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
My business partner Jake and I have been in the building trade for over 15 years. We undertake projects of all sizes, giving professional advice to meet your renovation needs. Our customers are aways highly satisfied, which intern leads to repeat business. The Grand Improvements team are polite, tidy, efficient, and take pride in completing every job to a high standard.
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Latest review:
Plastering- 24 Aug 2020
Byron replied to a job quickly, quote was what we have expected and he accomodated specific date we needed this done by. Communication from the beginning until the end was great, he explained everything clearly, advised day before what time will they be arriving and arrived in time. Did a fantastic job plastering living room ceiling and cleaned up the floor afterwards as well. Very pleased and will definitelly be employing again for any future jobs. Thank you!
Johny's Brickwork Ltd
Rating: 4.9 out of 5
Extension Builder in Welwyn Garden City
I have 7 years experience as a bricklayer and i ve done garden wallls, extensions, garages.
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Latest review:
Extensions- 6 Nov 2023
I hired John to do my Outbuilding Shell only. The work included demolishing existing structure, foundations, Block and Beam, EPDM roofing, Cavity Block works and Soakway. All aforesaid works were carried to highest standards and I am very pleased with works. John is friendly, reliable and trustworthy. I would use his services again and recommend him to others.
crimson kite construction
No reviews yet
Extension Builder in Welwyn Garden City
Fully experienced, impeccable attention to detail. Able provide a design service or complete a project to architect specifications.
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N.N2 GENERAL BUILDING
No reviews yet
Extension Builder in Welwyn Garden City
General building. EXTENSION, LOFT CONVERSION,GARDENS DESIGN,KITCHEN, BATHROOM, ROOFING,PLASTER &RENDERING, DECORATING, DRIVEWAY, PLUMBING, ELECTRICITY...
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RNB Construction
No reviews yet
Extension Builder in Welwyn Garden City
RNB Construction are able to offer a complete design and build package for the residential homeowner. We can help clients develop their concepts from ideation, through architectural interface, planning and into a high quality build. We also offer main contracting roles where clients have plans and permissions in place and are just looking for a high quality reliable builder to carry out their project. We were established to bring a professional approach to clientele looking for reassurance
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Marian Disca
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
Hi We undertake a variety of work,loft extension,bathrooms,kitchens,roofs,floors.etc With a experience of 15years there’s not much we haven’t done. Reference available!
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Latest review:
Joinery & Cabinet Making- 19 Apr 2019
Marian is i would say a master craftsman . He did an excellent job with the 2 alcove bookshelves. The alcoves were big and i wanted most of the period features and he made it exactly as per my specifications he also helped mount my tv on one of the units and looks very clean and he also helped conceal all wiring for my electric fireplace. I will definitely use his services again.
Solid building aspect Ltd
No reviews yet
Extension Builder in Welwyn Garden City
Solid Building Aspect Ltd is a specialist construction company delivering high-quality residential and commercial projects across London and Hertfordshire. With over 20 years of industry experience, we focus on extensions, structural alterations, renovations, and modern steel frame (SFS) systems — offering a more precise, efficient, and reliable way to build. We also design and build bespoke garden rooms and install premium aluminium and composite decking systems, creating functional, modern outdoor spaces tailored to each client’s needs. Our approach combines strong project management, attention to detail, and clear communication from start to finish. Whether transforming a home, adding flexible living space, or delivering complex structural works, we focus on results that add real value and stand the test of time.
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Breheny building and landscaping
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
We are professional builders with 4o years experience and 3 generations in the profession, pride our selves on providing good communication and quality of work , and we try to use environmental efficiency on all our projects . 40+ years experience in the building and landscaping trade , friendly and reasonably priced . We have folling certificates Level 2 brick work Street works licence All machinery licenses digger dumper etc Water civils and electric civils license Can supply grab lorry and have waste carrying license .
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Latest review:
Breheny builders visited my property gave me a quote and did a very good good job of the patio exactly in the time frame needed also within my budget they were well mannered and reliable I would definitely recommend and I will be using again to do my drive way
ELCarpentry
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
We specialise in bespoke carpentry , home extensions,renovations,commercial projects and property maintenance
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Latest review:
Conversions - General- 17 Jun 2025
Project was a little more difficult than I think was expected - but persisted and got it done. Thanks!
ERIC GROUP LTD
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
Eric Group Ltd has been trading for over 10 years and has completed numerous refurbishment and fit-out projects. We offer free survey and estimates and free specialist advice. If you want a new kitchen, a new bathroom, a house extension or a full house refurb, get in touch for a chat.
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Latest review:
The Job was to extend the rear of the house on the ground floor, open up the kitchen and reception room into one open plan living area, to refresh the rest of the house which included new plaster skim, doors and frames and to fit new bathrooms and kitchen as well as an rewire on the whole house and the construction of a retaining wall in the garden to accommodate the extension. Florins team were excellent from start to finish, the whole project was completed in record time to a very high standard. The 10 weeks turnaround was incredible, we were very happy that Florin was always here at the property or on the end of the phone throughout the process, his professional advice and smart ideas made for a smooth transition from room to room. The team were very hard working, polite and knowledgeable, these guys worked very hard and very quickly which was amazing to see and I was very grateful we were able to move into the property earlier than planned which even saved us money on the temporary accommodation we had! Can’t thank you enough Florin, any small issues we had were dealt with quickly and smoothly, I love the house, the level of work and would 100% use Florin and his team on my next project!
Woodberry London Limited
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
Woodberry London , is a personal, friendly company that is committed to meeting every customer's needs. We pride ourselves on our reasonable rates If you are looking for a professional service with high quality finishes, you can rely on us to deliver.
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Latest review:
Plastering- 9 May 2019
Charlie was very helpful, punctual and efficient.
Costa Boyer Ltd
Rating: 4.8 out of 5
Extension Builder in Welwyn Garden City
Costa Boyer Ltd provides specialist for complete building solutions:/conservatory/replacement windows/doors/home improvements/kitchen/garage conversion/house extension/garden shed/wooden decking/parquet/painted house/water leak/35 years experience building site. SCHUCO/ GQA Qualification Certificate of achievement in SCHUCO Curtain Wall/ GQA Level 3 Certificate in glass related operation/ GQA Level 3 NVQ Fenestration Installation, NVQ level 6, Covid-19 Essential: Infection Prevention and PPE
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Latest review:
Conservatories- 27 Jun 2026
Came in this morning and completed the job in a time manner. He checked and fixed all the panels. Very satisfied.

3.8

Top rated Extension Builders

Our Extension Builders in Welwyn Garden City, 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 Garden City?

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 Garden City 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 Garden City who are available and interested can respond to your post.

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

What are the hourly rates of extension builders in Welwyn Garden City?

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

Find extension builders in Welwyn Garden City with MyBuilder

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

Step 2: Compare different extension builders in Welwyn Garden City

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

Step 3: Hire Welwyn Garden City extension builders with confidence

After gathering all the information and quotes from your chosen home extension builders in Welwyn Garden City, 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 Garden City extension builders are ready to help. Use MyBuilder today to find the right professional for your home extension.

What to ask a Welwyn Garden City extension builder before hiring?

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

An extension builder in Welwyn Garden City 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 Garden City 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 Garden City?

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 Garden City 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 Garden City 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 Garden City

Can an extension builder in Welwyn Garden City help with planning permission?

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

Many Welwyn Garden City 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 Garden City help with materials and finishes?

Yes, most extension builders in Welwyn Garden City 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.