Extension Builders in Welwyn

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

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

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

1750 Results

Sort by:

Builder Cat LTD
Rating: 5 out of 5
Extension Builder in Welwyn
Serdar has over 20 years of experience as a professional builder. His extensive experience includes Owner/Builder/Developer of his own company, many years Builder Cat Limited was founded by Serdar Aydinlar, who has since 1996 structural engineering and design experience. Serdar oversees the structure of each project, and monitors the careful execution of the design brief to ensure a flawless finish.
Get in touch
Latest review:
Bathroom Fitting- 12 Jun 2019
Did a very good and efficient job with minimum fuss. I have asked the builder to quote for another job and do not have any hesitation in recommending this builder.
general builder
No reviews yet
Extension Builder in Welwyn
i do everything bathroom, kitchen, fencing, painting, flooring, driveway and many more but not electrical work and gas. im a handy man and general builder im reliable and good with price
Get in touch
Perfect Install LTD
Rating: 5 out of 5
Extension Builder in Welwyn
Perfect Install is an refurbishment and extensions specialist with 6 years experience in the building industry, doing all kind of projects, from small bathrooms refurbishments up to full house refurbishment including wall demolishing and building, flooring fitting, tiling, full kitchen design and fit and high quality painting. We do have in house authorised electricians and gas certified plumber. We have a history of projects started as small parts of a big project which end up with us doing the entire project at customer request. We are working in an 30 miles radius from Watford and we did projects in the medium to high luxury part of the building industry, including residential, commercial and public institutions. We offer to our customers an hassle free experience, getting involved in planning, sourcing the materials and advising regarding the local regulations. All our work is backed by an insured warranty which give our customers the peace of mind that the project is done at the highest level of quality.
Get in touch
Latest review:
Handyman- 28 Mar 2025
Amazing job, at a very fair price. The people who did the installation came prepared and were friendly, he even brought a laser to make sure the tilea were leveled.
Raghbir Singh
Rating: 5 out of 5
Extension Builder in Welwyn
Carpenter with 15 years of experience providing reliable, high-quality workmanship across Dunstable, Luton, Leighton Buzzard and surrounding areas. Specialising in all aspects of carpentry including first fix, second fix, doors, skirting, architraves, flooring, kitchen fitting and bespoke work. From small jobs to full renovations, all work is completed to a high standard with attention to detail. Reliable, punctual and tidy, with a focus on getting the job done properly and keeping customers satisfied.
Get in touch
Latest review:
Carpentry- 17 May 2026
Raghbir did an excellent job and completed the work on time, exactly as agreed. What stood out most was his honesty and professionalism there were no hidden charges or unexpected costs, which can often happen with some tradesmen. He also didn’t cut corners and delivered quality workmanship throughout. I would highly recommend him for any carpentry work.
crimson kite construction
No reviews yet
Extension Builder in Welwyn
Fully experienced, impeccable attention to detail. Able provide a design service or complete a project to architect specifications.
Get in touch
Concorde construction Ltd
Rating: 5 out of 5
Extension Builder in Welwyn
We cover all types of construction. From your small handyman jobs to building large extensions and summer houses. We specialise in all types of carpentry, bricklaying and decorating. We can take care of all of your building needs with plenty of recommendations. Look forward to hearing from you.
Get in touch
Latest review:
Extensions- 5 Oct 2022
I am very pleased with the work Josh and his team did in building my rear extension. They were a friendly and hard working bunch and very respectful of my space. Josh did a great job in project managing the work and making sure things were progressing as planned. Any snagging items were dealt with promptly. I would hire them again if required and recommend them to anyone who wanted to have building work done.
Redriver loft converters ltd
No reviews yet
Extension Builder in Welwyn
Welcome to Red River Loft Convertors Limited At Red River Loft Convertors Limited, we specialise in transforming homes with high-quality loft conversions, house renovations, extensions, bespoke kitchens, and luxury bathrooms. From initial design through to final installation, we provide a complete, end-to-end service tailored to your needs. Working closely with experienced architects and structural engineers, we can guide you through every stage of your project. Whether you're looking to create additional living space, modernise your home, or undertake a full renovation, our knowledgeable team is here to offer expert advice and professional support from the very beginning through to successful completion. With a commitment to quality craftsmanship, attention to detail, and excellent customer service, we take pride in delivering beautiful, functional spaces that enhance both your home and your lifestyle.
Get in touch
Handy builders stevenage
No reviews yet
Extension Builder in Welwyn
Local general building and maintenance brothers who come highly recommended and have been in the trade for a combined of 20+ years, no job too big or too small
Get in touch
RNB Construction
No reviews yet
Extension Builder in Welwyn
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
Get in touch
Slateriver Group Limited
New on MyBuilder
Extension Builder in Welwyn
Our highly-experienced team cover everything from light to heavy refurbishments, as well as new builds. We’re experts at transforming spaces, with minimal disruption. So, whether you need a brand new development or alterations to an existing space, we can navigate all the complexities on your behalf so that you can enjoy watching your vision emerge.
Get in touch
Herbert property services Ltd
No reviews yet
Extension Builder in Welwyn
Herbert property services Ltd is a local building company committed to focusing on our customers’ requirements. We offer a complete service from design to build and will arrange a visit, at a time to suit you, to discuss your project. We will then provide a free, no obligation estimate. We have a reputation for carrying out high quality work and pride ourselves on our ability to provide exactly what the client is looking for, without compromising on quality or altering the original design.
Get in touch
I&A Construction Ltd
Rating: 5 out of 5
Extension Builder in Welwyn
I&A construction Ltd has been trusted name in construction and renovation,including bathrooms, kitchens,interior and exterior work.
Get in touch
Latest review:
Ion was done extension and refurbishment in the whole home.Speed and quality purposes were much pleasant given by the professional workers.
Vines Construction Ltd
No reviews yet
Extension Builder in Welwyn
Vines Construction Ltd Specialise in all areas of the residential construction industry. Bespoke extensions & boutique refurbishments are our forte.
Get in touch
O.L.T.O CONSTRUCTION Ltd
Rating: 5 out of 5
Extension Builder in Welwyn
we are able to undertake any work that has to do with the interior and exterior of your home. Responsibly!
Get in touch
Latest review:
They did an amazing job of our extension from initial quotation right the way through until project completion. Communicated very well and all of the team were respectful and hard working throughout each stage of the project. Would highly recommend!
ALLARAJ BROTHERS LTD
Rating: 5 out of 5
Extension Builder in Welwyn
Welcome to ALLARAJ BROTHERS LTD At ALLARAJ BROTHERS LTD, we pride ourselves on delivering excellence in every project we undertake. With decades of experience in the construction industry, we have established a reputation for quality, reliability, and customer satisfaction. Our team of skilled professionals is dedicated to bringing your vision to life, whether it's a residential, commercial, or industrial project. We use the latest technologies and sustainable practices to ensure that every build is not only beautiful but also durable and environmentally friendly. We understand that each project is unique, and we tailor our services to meet your specific needs and preferences. From initial consultation to project completion, we work closely with you to ensure that every detail is executed to perfection. Choosing ALLARAJ BROTHERS LTD means choosing a partner who values integrity, transparency, and excellence. Let us help you create spaces that inspire and endure. Contact us today to discuss your next project and experience the difference that true craftsmanship and expertise can make.
Get in touch
Latest review:
Restoration & Refurbishment- 5 Jan 2025
Very happy with the professionalism, and friendly polite communication. Adem is a perfectionist and can see things I noticed no one else could. The quality of workmanship was excellent. Will definitely be using them again.
Dj Russell builders limited
Rating: 5 out of 5
Extension Builder in Welwyn
We are a building company which cover a multitude of trades in the industry. We pride ourselves on quality and good working relationships with all our clients. We have been trading for over forty years and have built up a good reputation with local authorities and domestic clients alike. We cover all building and maintenance aspects in the private and public sector.
Get in touch
Latest review:
Extensions- 14 Feb 2021
Adam and the DJ Russell team have been great, I cannot recommend them highly enough. The job started on the 3rd of November 2020 and was completed on the 3rd of February 2021. All the neighbourhood have been impressed with the speed and accuracy of workmanship displayed. From the general builders (Bruce, Martin and Steve) to the brickies (Paul, Matt and Steve) and to the carpenters (Paolo and Dominic) through to the electricians (Max and his team) and the plumbers (Mark and Jack) and last but not least the plasterers (Gary and Craig) they all have kept me occupied with producing huge quantities of tea and coffee (-: but most of all they have constructed a quality extension for our home. Thank you for all your hard work and professionalism.

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

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?

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.