Extension Builders in Welwyn Garden City

Name: Extension Builder
Brand: MyBuilder
SKU: extension-builder
Rating: 3.9 (15 reviews)

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Some of our top rated extension builders in Welwyn Garden City

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Zenstruction
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
Established in 2005, we are a trusted building company with extensive experience in all aspects of construction, from new builds to fascia and gutter installations. Known for delivering high-quality projects on time and within budget, we maintain the highest standards of workmanship, safety, and reliability. Our expertise spans a wide range of services, ensuring that each project is completed to exceptional standards, meeting both client expectations and industry regulations.
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Latest review:
Extensions- 3 Sep 2018
Zen has helped transform our home, we’ve drawn a lot of confidence from his considered approach and thorough work ethic. He’s so far addressed the cause of cracks to exterior walls of our property and has provided lasting solutions. We also asked him to plaster our hallway and update the banisters for us, Zen has done a great job of reinforcing the strength of the original features whilst retaining the property’s character. Very good with pets too. Looking forward to the next project.
Leni Muca Builder
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
My name is Leni I have 8 years experience on home improvements. Kitchens, Bathrooms, tiling, flooring, carpentry, electrical, plumbing, handyman. I guarantee a professional work to be done. My priority is to make clients happy with the work I do. I promise you will not be disappointed from Leni Muca Builder. Thank you.
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Latest review:
Bathroom Fitting- 3 Dec 2020
10/10, would recommend to anyone. High quality of work, very helpful and punctual.
BUILD ON TIME LTD
Rating: 4.9 out of 5
Extension Builder in Welwyn Garden City
BuildOnTime LTD is a family business and one of the fastest growing building companies in London.We have over 20 years of experience in all types of building and construction works.Our team is structured from highly qualified, friendly and ambitious workers.We are your builders in North London.
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Latest review:
Extensions- 30 Aug 2024
We recently used Build on Time Ltd to build a ground floor extension and remove chimney breasts from 4 rooms on a home renovation project. Paul and his team delivered within budget and ahead of time. This did not compromise their attention to detail or care taken with their work. All were extremely hard working and committed to getting as much out of each day as possible. They were reliable, trustworthy and a pleasure to be around. We would definitely recommend!
Integrated Homes Ltd
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
Integrated Homes Ltd are a family run construction founded in 1997. We specialise in extensions, conversions and renovations. We also work with architects so are able to assist with the design stage of your build.
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Latest review:
We recently completed a large renovation which included extending our kitchen at the rear of the property, changing levels in the garden and converting our loft with an additional bedroom and en-suite. Ben, Steve and the rest of their team were amazing throughout. We had difficulty moving out of the property as our short term let fell through but the team worked tirelessly to enable us to ‘live in’ whilst much of the build was going on (which I know wasn’t ideal!) I highly recommend Integrated Homes as Ben and Steve were so knowledgeable, considerate and professional in their work.
TCBUILDERS LTD
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
I have over 20 years experience in carpentry and joinery, building and refurbishment works, kitchens and bathroom installation, design and build, landscaping and garden rooms. I have worked in construction from an apprentice carpenter to site management on new builds and residential works. Delivering quality is my aim no matter size or cost.
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Latest review:
Bricklaying- 26 Nov 2021
The guys did an excellent job re-laying the coping stones - responded promptly and came to price up quickly, friendly and professional! Wall looks so much better.
KB building and carpentry
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
Hi I'm 52 years old i cover all aspects of carpentry . With my years of experience of running new build and extensions I've come across lots of issues to over come with myself and other trades. I have good network of trades I've worked with over the years that I can also rely on and trust to deliver a great project. My attention to detail and finishing a job also comes with my length of time In this industry. There isn't a job I wouldn't consider being it a secret door into a gym. Which I have not long finished. To building a house from the footing to finish. O will help design a project and also follow a drawing and deliver as expected. I have a full range of photos and also a list of happy clients that I can introduce you to.
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Latest review:
Carpentry- 25 Oct 2025
Kevin carried out an excellent job fitting a door and adding handles to other doors. Polite, tidy, and professional. Would definitely recommend.
Mars Building
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
Mars Building is a local family run business with four generations of experience in the building and carpentry trade, all our workers are fully qualified and all our work is fully insured so if we're in your house you know you're in safe hands
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Latest review:
Carpentry- 19 May 2014
Ricky did an excellent job of removing and replacing my rear garage door, as quoted and kept it clean.
Devi
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
Shehu builders With many years of experience in construction industry, I work to very high standards and my customers are always extremely satisfied with my work.
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Latest review:
Restoration & Refurbishment- 3 Oct 2025
Devi is a very nice, polite and more importantly calm man. He has just finished renovating our entire flat to a very good standards. Thank you Devi!
D Halpin
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
Hi my name is Dan I have been bricklaying for over 20 years.i don’t mind what the job is small or big and I am responsible priced
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Latest review:
Bricklaying- 5 Jan 2026
Would thoroughly recommend Dan. He was friendly, prompt and did a great job repairing our brick wall.
Go&Ko Services Ltd
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
Go&Ko Services LTD is a 24 hours Property maintenance company for the Public and Commercial with trust and confident in quality and high standard services. Our offers the following services on a residential and commercial basis: - General Building/Extension - Loft conversion - Refurbishment - Kitchen/bathroom installation - Carpentry - Tiling/Flooring - Plumbing - Drainage - Metal restoring/welding - Electrical - Decorating - Handyman - Fencing/Decking -
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Latest review:
VERY PROFESSIONAL WORK AND GOOD COMMUNICATION
Basil Brothers
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
We are an experienced team formed of two brothers who have 15 years experience in building and interior and exterior renovations. We have experience working both in the UK and across Europe. We have a good track record of quality work and we can provide UK references on request.
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Latest review:
Extensions- 14 Apr 2019
These guys have done an incredible job with my extension. They are professional and friendly and I can't fault them once in three weeks! They not only completed the job quickly, but without cutting any corners either. I wish more builders had this level of care and work ethic!
Propertkare
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
Propertkare is service run building and refurbishment group. We undertake all forms of building work and maintenances, kitchen and refurbishment, painting and tiling. We have been trading for past 10yrs with great success.
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Latest review:
Carpentry- 14 Oct 2025
Mr Williamson did a fantastic job installing and repairing fire doors in my HMO property to the exact standard required by the council. He was very professional, punctual, and highly attentive to detail throughout the entire project. The quality of his work was exceptional, and he ensured the job was completed within the agreed deadline. I’m very pleased with his service and would gladly recommend him to anyone looking for a reliable and skilled carpenter.
BACK 2 NU Handyman Services
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
BACK 2 NU Handyman Services. Established in 2006, many years of building and property maintenance experience. We do small jobs as well as big projects.
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Latest review:
Handyman- 1 Feb 2021
Very pleased with the job Artur completed (2 shelves and curtain brackets to put up). Very professional, arrived ahead of agreed time. Highly recommended. I will not hesitate to contact him for future jobs. Many thanks
Bathroom fitter,Handyman,Plumber,Electrician
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
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:
Restoration & Refurbishment- 15 May 2026
Daniel and his team were excellent. Always on time, polite, and flexible. They did a fantastic job with this garage conversion & painting. The end result looks great. Would highly recommend
Sinevir Construction
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
Sinevir Construction Ltd is a trusted construction company based near London, proudly serving the capital and surrounding areas. We specialise in residential and commercial projects, including new builds, extensions, refurbishments, and structural works. Our team of qualified professionals is committed to: High standards of workmanship Full regulatory compliance Clear and honest communication throughout every stage of the project Whether it's a small private renovation or a complex public contract, we approach each project with care, precision, and professionalism. What sets us apart: ✅ Construction Online Gold Member ✅ Skilled and experienced workforce ✅ NEBOSH-certified site safety supervision ✅ CHAS and SSIP-accredited for health & safety standards ✅ Fully insured, giving clients peace of mind ✅ Transparent pricing and realistic scheduling ✅ Respect for architectural heritage and local communities ✅ Competitive rates without compromising on quality We believe every property deserves thoughtful construction and reliable service — and at Sinevir Construction Ltd, we proudly deliver both.
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Latest review:
Extensions- 27 Mar 2026
Ruslan was excellent at his craft. Very hard working, very clean and professional with a great attitude. Would highly recommend this company
U & A Builder
Rating: 4.9 out of 5
Extension Builder in Welwyn Garden City
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!

3.9

Top rated Extension Builders

Our Extension Builders in Welwyn Garden City, are rated 3.9 out of 5 based on 15 reviews from customers like you.

Quality screening

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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.