Extension builders in Welwyn Garden City

Name: Extension Builder
Brand: MyBuilder
SKU: extension-builder
Rating: 4.6 (17 reviews)

Easily find verified Welwyn Garden City Extension Builders. Just post your job to get quotes from MyBuilder's Extension Builders in Welwyn Garden City.

Select a service

How it works

Post your job for free

Tell us about your job, and we’ll alert suitable tradespeople in your area. It’s simple and free.

Tradespeople respond

Once your job is posted, you’ll get responses from interested tradespeople through the website.

Review profiles and choose

Browse profiles, work history, and feedback, then choose who you wish to share your details with.

Some of our top rated extension builders in Welwyn Garden City

1978 Results

Sort by:

J.M Roofing & Building Services
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
Based in Luton/Dunstable we offer top quality workmanship in all aspects of roofing and building. we pride ourselves not only in being friendly and reliable, but professional and competitively priced. All our tradesmen are fully qualified and all our work is fully insured and guaranteed.
Get in touch
Latest review:
Had roof serviced and re-cemented ridge tiles. He kept great communication, was very professional and polite. The workmanship was to a high standard from what I can see and once finished all was left clean and tidy.
Cani 1 construction
Rating: 4.7 out of 5
Extension Builder in Welwyn Garden City
we have a construction company we are in the happy position to fulfill each one separately our company is family owned we have been in this area for over 15 years, we offer (brickowork)🧱 face bricks face blocks garden wall retaining wall extension new building new house Repoiting landscape design & builds🏜
Get in touch
Latest review:
Bricklaying- 17 Aug 2026
Rear single storey extension, they do the job professional!! Highly recommended!!
steven group
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
Heb_limited is family business which is specialised in Loft Conversions , Extensions and all building fields .
Get in touch
Latest review:
Extensions- 14 Mar 2024
Stefan initially quoted for our extension however, we used them for a few other jobs instead namely summer house, now the porch at the front of the house and will be using him for our garden and driveway work. He is very professional and has completed the work with a very high standard. His team are very claim and make sure that there is no mess left at the end of the day. Great communication. Would highly recommend hence why we are using him for other work and I have recommended him to family members.
P C Bondea Limited
Rating: 4.8 out of 5
Extension Builder in Welwyn Garden City
I'm very punctual, reliable and sociable. Attention is paid to every detail. I always treat customers with respect, and my moto is: If a job is worth doing, it is worth doing properly. Everything is left clean and tidy. My focus is on ensuring a quality job and making the customer happy.
Get in touch
Latest review:
Handyman- 26 Oct 2026
Punctual, tidy and got all the jobs completed quickly and to a high standard.
SS Carpentry
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
I have done jobs from shelving to roofing.I have a good job knowledge and I have ran big site. I have been a carpenter for 6 year and normally do first fix work but I can do second fix , kitchen fixing and plasterboard. I have all the tools to do the jobs with.
Get in touch
Latest review:
Carpentry- 28 Aug 2018
Steve is punctual, easy to work with, hard working with all the skills, knowledge and experience to efficiently produce a successful result- replacing old floorboards and removing squeaks in steps- recommended and known from this job alone.
Linear Carpentry & Building
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
Hi, I'm James – with over 15 years of experience in the carpentry and building trade. Based in Much Hadham, Hertfordshire, we take on projects of all sizes, delivering high-quality craftsmanship with attention to detail. We proudly serve clients across Hertfordshire, Essex, and Cambridgeshire, covering any job within a 30-mile radius. Whether it's a small renovation or a full-scale build, we're here to help bring your vision to life.
Get in touch
Latest review:
James managed our kitchen extension project and took ownership of all carpentry, and we couldn’t have been happier with the outcome. The project was delivered smoothly and to a high standard, and James was a pleasure to have working at our home. We especially loved the outdoor pergola / cinema area and hot tub decking he built too, which was technically quite challenging and looks absolutely fantastic. I would absolutely recommend Linear Carpentry to friends - and have done!
EBV construction
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
All building construction loft conversion Extension Refurbish Carpenter Plastering rendering Dry lining Garden walls
Get in touch
Latest review:
Plastering- 22 Jul 2023
Mr Meta and his skilled team completed the plastering job as promised with high standard,good, honest and profesional. Will be hireing on other jobs.Many thank👊👍
Plasterer
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
With over 9 years experience and a real focus on customer satisfaction, our team of experienced professionals will produce a smooth finish every time on your walls and ceilings. We also do all aspects of rendering and EWI SISTEM (external wall insulation ). Always on time and on budget.
Get in touch
Latest review:
Insulation- 5 Sep 2024
Fantastic work by Andrei, Ciprian and their team. Highly skilled and hard working team, starting on time (8am) every day and working until late, clear communication as the job was progressing, clear and fair pricing, attentive to details, and happy to accommodate non-standard request like 100mm EWI. Highly recommended!
Paul Cusack
Rating: 4.9 out of 5
Extension Builder in Welwyn Garden City
Carpenter.20 years experience. 1st and 2nd fix, roofing, kitchen fitting. All carpentry works.
Get in touch
Latest review:
Carpentry- 7 Mar 2021
Great service and value for money. We commissioned Paul to build a garden office. The job was completed in less time than originally expected and the quality of the workmanship was excellent. I have no hesitation in recommending Paul and we have already passed his details on to a neighbour who wants a garden studio built. We will also hopefully be using Paul's services again in the future on a loft conversion.
andrew mellish plumbing and heating services ltd
Rating: 4.6 out of 5
Extension Builder in Welwyn Garden City
My name is Andrew Mellish, and I run Andrew Mellish Property Home Services. I am 39, married, with 3 sons. My team is made up of 6 full time tradesmen. We take on all domestic build/renovation projects. With decades of experience within the team, you can be assured of the highest standards.
Get in touch
Latest review:
Bathroom Fitting- 10 Nov 2013
Andy and his team did a good job replacing our bathroom and cloakroom. The job overran due to a couple of logistical problems with different tradesmen, but Andy did his best to minimise the disruption. Good communication and accurate quote, which was stuck to. Overall, we're happy with the outcome.
JP’s Brickwork/Restoration
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
I'm a bricklayer with 30 years experience, I also undertake many general building works. I produce quality work and am always ready to give advice where needed, brickwork and restoration is my normal workload but do undertake a lot of landscape works. I am based in Essex and work in and around the surrounding counties, polite reliable service given everytime. I pride myself on making the customer happy with the work I complete.
Get in touch
Latest review:
Extensions- 21 Mar 2019
Really nice bloke. Honest, reliable,keeps you updated on what's happening and the next steps. Will give any advice when needed. Not pushy,and looks to look after customer as best as possible regarding cheapest option available. Very tidy, and does a really good job. Would have no trouble in hiring Jim for any other work required. Fully recommend.
Icv Building SERVICES
Rating: 4.5 out of 5
Extension Builder in Welwyn Garden City
We are a professional construction team. Our services include: New Builds Residential and Commercial Refurbishments Tilling Electric Plumbing Gardening & Landscape Painting and decorating External painting Paint spraying Plastering Dry wall Carpentry Kitchen and bathroom fitting And much more All for a very competitive price!!! Contact us today for a FREE QUOTE!
Get in touch
Latest review:
Restoration & Refurbishment- 11 Sep 2024
I gave them work worth over £21000. They were good at doing the ceiling work but I am not happy about the way they left the bathroom. There are places where they have not done grouting and parts of the radiators, holes, left without completing. Damages to my staircase, very expensive French wood wardrobe my double bed and my chandeliers were just left without being fixed.
Gh building
No reviews yet
Extension Builder in Welwyn Garden City
Gh building have over 25 years of building experience, completing a variety of projects. All brickwork undertaken. Ground works Driveways Extensions Garden walls Landscaping
Get in touch
Horwood homes and construction Ltd
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
At Horwood Homes and Construction we aim to work with our customers to achieve projects to the highest standard, using our experienced team of brickwork specialists, we help you to plan and build any job size from garden walls to complete new build projects. After many years of working with bespoke builders we have gained the ability to complete the most challenging of builds and we believe any job is possible with good communication, a clear understanding and a passionate team. Please get in contact with us today for any advice or a free quotation. Please check us out on Instagram (horwood_brickwork) Or Facebook and Checkatrade (Horwood homes and Construction) Thanks Horwood_hc
Get in touch
Latest review:
Highly recommend Phil. He took time to understand my requirements and offered a competitive price for the job. Work was completed in a timely manner and to a very high standard. Thanks Phil I will be using you again in the future for any building projects. ⭐️⭐️⭐️⭐️⭐️
Cs ideal builders ltd
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
We are more than a construction company — we are builders of trust, quality, and lasting value. With a passion for excellence and a commitment to precision, we deliver outstanding results in residential and commercial construction, renovations, and structural projects of all sizes. Every project we take on is driven by craftsmanship, attention to detail, and a deep understanding of our clients’ vision. Our experienced team combines modern techniques with proven expertise to create spaces that are not only functional, but truly exceptional. We believe that great construction goes beyond materials — it’s about reliability, transparency, and strong partnerships. That’s why we prioritize clear communication, on-time delivery, and uncompromising quality in everything we do. From concept to completion, we turn ideas into reality and ensure every detail is built to last. Our mission is simple: to exceed expectations, deliver excellence, and build spaces that stand the test of time.
Get in touch
Latest review:
Carpentry- 15 Apr 2026
Ionut and his team arrived on time, assessed the job and offered to do it on the spot. Looks like a job well done and price was reasonable. Nice one
Mmk contractors ltd
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
⁦here at MMK contractors our professional and well-mannered painters will make your bedroom, living room, kitchen, office or any other room look good whatever colour you decide. We focus on quality and client satisfaction, we bring your vision to life.
Get in touch
Latest review:
Painting & Decorating- 4 Oct 2026
Ali was excellent, he provided advice, guidance and delivered a brilliant job with attention to detail in exactly the timeframe needed. No task was too small. We were really happy with his work and his pricing was competitive too. Highly recommend :)

4.6

Top rated Extension Builders

Our Extension Builders in Welwyn Garden City, are rated 4.6 out of 5 based on 17 reviews from customers like you.

Quality screening

Easily find verified local tradespeople. Just post your job to get quotes from tradespeople near you across the UK.

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.