Extension builders in Welwyn Garden City

Name: Extension Builder
Brand: MyBuilder
SKU: extension-builder
Rating: 4.6 (16 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

1990 Results

Sort by:

Medi Building and Construction
No reviews yet
Extension Builder in Welwyn Garden City
As I need to improve my Mybuilder feedback, I would not worry about the price of your job. So it is a great opportunity for you to get your work done in the best possible way and minimum price. Although we are new in Mybuilder, we are professional and qualified team in many construction aspects with over 20 years experience. We want to make sure that you get what you want at the highest standard and minimum price. Please don't hesitate to contact me for any reason. Many thanks Mehdi
Get in touch
HNL Construction Limited
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
Home improvement company. Experience since 2005.Our job is our passion.Let us make Your dream project.Every job its important to us from small to big. We do: -kitchen -bathroom -loft conversion -extension -refurbischments -electric -plumbing -gardening …and many more
Get in touch
Latest review:
Conversions - General- 23 Mar 2026
Pawel and his team are great - got them in for a few things now, from damp repair, knocking through an internal brick wall, moving a fuse box, installing a wood floor. Always good workmanship, easy comms and decent value! Have recommended to a few friends who are equally pleased.
P O'Brien Builders London LTD
No reviews yet
Extension Builder in Welwyn Garden City
P O’Brien Builders is a trusted, family-run building company with decades of experience delivering high-quality construction services across London. We specialise in home renovations, extensions, loft conversions, and new builds, offering a reliable and professional service from start to finish. Our reputation is built on quality workmanship, attention to detail, and clear communication throughout every project. Whether it’s a small upgrade or a full renovation, we approach every job with the same level of care and commitment, ensuring results that are built to last. As a family business, we take pride in what we do. With the next generation now involved, we combine traditional values with a modern approach to building, giving our clients confidence in both the process and the final result.
Get in touch
Lcd
Rating: 1 out of 5
Extension Builder in Welwyn Garden City
Hy I am cris more 15 years experience in carpentry and building work
Get in touch
Latest review:
Joinery & Cabinet Making- 8 Jan 2024
Absolute cow boy 🤬 Don’t even think of hiring So many faults Door not closing Plinth boards cut wrong So much more disgrace
Bealls Carpentry and Building services
No reviews yet
Extension Builder in Welwyn Garden City
Bealls Carpentry and Building Services continues to deliver spectacular projects to the highest standard. High quality workmanship completed to health and safety regulations and planning permission with certified engineers that are fully knowledgeable on the most up to date electrics, plumbing and heating solutions. We work with you to bring your project to life offering a complete service from the initial idea through to architectural design and build.
Get in touch
Florin Stancu
No reviews yet
Extension Builder in Welwyn Garden City
My business consists in undertaking various aspects of construction and building. I’ve been in the business for about 15 years doing both site and private work. The type of work that I usually do is: - extensions - bricklaying - refurbishment
Get in touch
T & D Barrs Plumbing and Heating Ltd
No reviews yet
Extension Builder in Welwyn Garden City
We provide a reliable, efficient service; on time and to budget, keeping large and small business operations running efficiently and safely. From routine repairs and maintenance through to complete project management. Our Services cover: • Central Heating & Plumbing • Electrical • Building Services & Project Management • Carpentry Works • Gas We are a family business, independent of any other organisation, established in 1997. We are an environmentally aware company and are proud to have achieved ISO14001. Be reassured: with T&D Barrs you’ll receive unbiased advice, a fair price and quality workmanship consistently.
Get in touch
WS Building
Rating: 4.8 out of 5
Extension Builder in Welwyn Garden City
I am Builder with 30 years experience in all kind of building projects.Together with my team we can provide for you a complete building service and help with advice in any aspects of building works. We specialise in: conversions, extensions, renovations, reconfigurations, basements, lofts, new kitchens and bathrooms, flooring , doors, gardening, demolition works, roofing, steel installation, plastering, painting and decorating and all others of building works included electric and plumbing.
Get in touch
Latest review:
Restoration & Refurbishment- 10 Nov 2025
Professional and on time, recommended
Garnet Construction Ltd
Rating: 4 out of 5
Extension Builder in Welwyn Garden City
Garnet Construction has over 10 years' experience in the industry and specialise in loft conversions, all types of extensions and complete renovations. Priority is given to the design and construction of all our projects with a unique obsession to strive for perfection.
Get in touch
Latest review:
Extensions- 18 Sep 2019
To start off with the job went reasonably well - we were happy with the workers and the progress. but when we neared completion the work slowed up we waited 3 months for a response from Jordan. we had an issue where his plasterer hid the plumbing access in the wall. - This cost us £500 to sort and re-decorate so we came to an agreement that this was fine and at the time i presumed that Jordan was going to sort out the building control. so we then chased and chased but obviously since he had his money he wasn't interested he answered the phone and hung up. so we called building control and there are 2 small bits to fix which are all due to his work not being up to scratch. obviously i will be paying out for this - so please be careful when using him and dont pay him until you have all of the documents as he will not resolve any issues after being paid. i have had 2 previous building projects and this was by far the worst experience going. avoid dont use him thanks
LIVAHAUS
Rating: 5 out of 5
Extension Builder in Welwyn Garden City
We are a professional team and we are very responsible, punctual and on time with our work .
Get in touch
Latest review:
Tiling- 16 Feb 2026
Luis did an excellent job on my bathroom. He had to do a lot of prep work before starting the tiling, including rebuilding the floor and repairing the walls. At every stage he explained what needed to be done, ensured that I wanted to go ahead, listed the materials that would be needed, and the cost. It made a huge different to me that Luis was willing to source and purchase all materials; he checked in with me from the suppliers as to choice and cost, and sent receipts for every penny. I cannot recommend him highly enough, for his knowledge and expertise, his honesty and hard work, and also for being such a lovely person, nothing is too much trouble. I am delighted with my new bathroom, and am planning more home improvements with Luis, when he is free again!
Acme Lofts & Extensions Ltd
No reviews yet
Extension Builder in Welwyn Garden City
Acme Lofts & Extensions specialises in the construction of Loft Conversions & Domestic Extensions. Based in Enfield, covering Greater London & Herts, we have over 30yrs experience & expertise in this industry. Our team of skilled tradesmen, qualified technical engineers, professional architects & surveyors will create the highest quality & most desirable living space for your project. All work is guaranteed, insured, vetted & monitored.
Get in touch
Paternoster building services limited
No reviews yet
Extension Builder in Welwyn Garden City
With 20 years of experience in the building industry, I have successfully managed a wide range of projects, from small-scale bathroom renovations to large, complex refurbishments and extensions, including bespoke features such as saunas, steam rooms, gyms, and frameless glass balconies. I began my career mastering the wet trades, groundwork, and drainage, before transitioning to a role with a company that allowed me to broaden my expertise across all areas of plumbing. Over time, I specialized in bathroom fitting, honing my skills in high-quality bespoke installations and design. Upon founding my own company, I chose to focus on property development and extensions, driven by a passion for witnessing the complete transformation of properties. This experience has enabled me to deliver exceptional results and exceed client expectations on every project.
Get in touch
R a Daniels
No reviews yet
Extension Builder in Welwyn Garden City
Home extensions ,any type of building works
Get in touch
Raf Building Services
No reviews yet
Extension Builder in Welwyn Garden City
Fully qualified carpenter, NVQ3 , insured and happy to help.. No job to small or to big - from flat pack furniture to complete loft covertion.
Get in touch
Gabriel Slavik
No reviews yet
Extension Builder in Welwyn Garden City
I’m doing building work for last last 23 years. I always try to do precise work, I am happy to help and advise the customer.
Get in touch
D inch property development
No reviews yet
Extension Builder in Welwyn Garden City
I have 30 yrs in the building industry from fitting kitchens & bathrooms to building houses from the first brick upwards, extensions loft conversions . I pride myself in being very professional at all times .
Get in touch

4.6

Top rated Extension Builders

Our Extension Builders in Welwyn Garden City, are rated 4.6 out of 5 based on 16 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.