Extension Builders in Welwyn

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

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N.N2 GENERAL BUILDING
No reviews yet
Extension Builder in Welwyn
General building. EXTENSION, LOFT CONVERSION,GARDENS DESIGN,KITCHEN, BATHROOM, ROOFING,PLASTER &RENDERING, DECORATING, DRIVEWAY, PLUMBING, ELECTRICITY...
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NESIMI CONSTRUCTION LTD
Rating: 5 out of 5
Extension Builder in Welwyn
Nesimi construction ltd With over 18 years of experience, we specialise in bricklaying, driveways, and paving. We carry out all types of work including garden walls, patios, extensions, repairs, and general building. We pride ourselves on high-quality workmanship, reliability, and attention to detail. All jobs are completed to a high standard, on time, and at competitive prices. Friendly, honest, and professional service from start to finish.
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Latest review:
When Mr Nesimi came to undertake a pre-assessment for my front wall, he came across very professional and genuine and very honest about the work needed doing. He even suggested some changes to the work to reduce cost. The quote he gave me for the job was very reasonable and he was able to slot in my job within a week and arrive sharp on time at 8am and got on to the job straight away as I had a busy day at work for me to attend to. I notice that right from the start he was very clean and meticulous with the work and his job was of a very high quality ( compared to a job I had done by another builder 9 months ago). My neighbours also noticed this difference and were praising Mr Nesimi’s work. I would definitely recommend Mr Nesimi for any construction work as I felt he was very professional, reliable and honest and most of all the work was of high quality. I will be certainly calling him for my next job, most likely the driveway resurfacing and the attic conversion within the next year.
K build
Rating: 4.4 out of 5
Extension Builder in Welwyn
About Us With over 25 years of experience in the UK construction industry, our team provides a full range of high-quality building services for homes and properties across Luton and surrounding areas. We specialise in all aspects of domestic plasterwork, painting, plasterboarding, stud walls, carpentry, bathrooms, kitchens, extensions, roofing, and driveways — handling every stage of the project with care and precision. We pride ourselves on our attention to detail, cleanliness, and reliability. Our goal is to deliver outstanding workmanship at fair and reasonable prices, ensuring every customer is completely satisfied with the results. No job is too big or too small — all types of building work are undertaken with the same dedication and professionalism.
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Latest review:
Plastering- 15 Aug 2022
Skimming job completed quickly but now that decorations have started the painters are picking up ripples in some of the walls that rushed.
Stable Construction
No reviews yet
Extension Builder in Welwyn
We cover all types of work, ranging from patios and ground work to loft conversions and extensions. Our team are always polite and offer their professional options when required.
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Imperium Build
No reviews yet
Extension Builder in Welwyn
Bricklayer for 26 years doing my own building work for last 12 years extension new builds al aspects of building start to finish,paving patios.internal steel works
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ASG Developments - Herts
No reviews yet
Extension Builder in Welwyn
Free Architectural Plans Included with every build. Crafting timeless spaces with precision, passion, and purpose. Welcome to ASG, where visionary architecture meets exceptional construction. From concept to completion, we bring your ideas to life with innovative design, sustainable practices, and uncompromising craftsmanship. Whether you're planning a custom home, commercial space, or renovation, we deliver spaces that reflect your vision — beautifully and efficiently.
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ELCarpentry
Rating: 5 out of 5
Extension Builder in Welwyn
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!
CJ Property Improvements
Rating: 4.7 out of 5
Extension Builder in Welwyn
Here at CJ Property Improvement we pride ourselves on being reliable, friendly and clean. Our most used tool is the vacuum cleaner, it is always the first tool off the van and the last back on. We ensure every job we carry out is to the highest standard and to your complete satisfaction, no matter how big or small. Although we are a new company we have plenty of experience. Below is just a sample of the work we have carried out since we opened in 2017. There are plenty more pictures to see
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Latest review:
Bricklaying- 8 Oct 2022
Good comms, quick and tidy work.
Cinnamon Design Studios Limited
Rating: 4 out of 5
Extension Builder in Welwyn
Avenue Developments is a development consultancy, taking projects from inception to completion, in time and within budget. We offer our clients a tailored service, by evaluating each project to identify where value can be added and where potential problems may arise. We are committed to the quality of our professional service and have proven to satisfy our client's expectations.
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Latest review:
CAD / Drawings- 6 Dec 2019
Lack of professionalism! Called me at 2150 to say was interested in job, warning signal but said far enough so booked an appointment. He didn’t turn up nor respond to my texts asking if he was held up somewhere. I am not sure how trustworthy he is.
What 4 Building Solutions LTD
Rating: 4 out of 5
Extension Builder in Welwyn
Here at What 4 Building Solutions LTD, We cover all aspects of the of the building process. From helping with design using our amazing architects. Getting your ideas through planning and building regs, then making your dreams come true. We cover Herts, London, Essex & Cambridgeshire. Taking on any size project from new builds to a refurb or even just a new kitchen we can help. We offer man and machine hire and licensed waste removel. We have all the trades on hand ready to go so we have no delays on our projects. We have the SOLUTION for your project... We are pround Members of the Federation of Master Builders and TrustMark the only Government Endorsed for Quality work.
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Latest review:
Extensions- 21 Mar 2026
I am a Chinese Lady honourably established at Hollyview Close, London NW4 3SZ, of at least sixty years of age, and distinguished by the wearing of spectacles, which bespeak both careful attention and the wisdom accrued through decades of devoted service. I am entrusted with the disciplined and esteemed practice of electrical repair and maintenance, a vocation carried out with the utmost reverence for order, propriety, and the impeccable standards befitting households of the highest esteem. Upon my arrival, I bring forth with equal dignity both the meticulous execution of all electrical works and the ceremonial offering of fine chewing gum, bubble gum, and freshly selected lemons, each item presented with deliberate attention to freshness, quality, and presentation, in the grand tradition of British hospitality and courtly decorum. The chewing gum is carefully curated to encourage measured mastication, fostering calm, poise, and contemplative steadiness; the bubble gum is reserved f
steven group
Rating: 5 out of 5
Extension Builder in Welwyn
Heb_limited is family business which is specialised in Loft Conversions , Extensions and all building fields .
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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.
London plumbing and heating
No reviews yet
Extension Builder in Welwyn
7 years experience on plumbing gas domestic boilers heating bathrooms and kitchens ltd company
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J.M Roofing & Building Services
Rating: 5 out of 5
Extension Builder in Welwyn
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.
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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.
JNH Builders
No reviews yet
Extension Builder in Welwyn
JNH Builders are a local building company based in Hertfordshire specialising in home extentions and brickwork, however all aspects of building work are undertaken. At JNH Builders we take pride in ourselves by keeping all work to a high standard at competitive rates, and insure you'll be kept up to speed with all job progress.
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Everything! Build and maintain
New on MyBuilder
Extension Builder in Welwyn
With over 30 years experience in the building trade, we bring a wealth of knowledge and hands-on expertise to every project. Our team covers all aspects of building and maintenance, delivering reliable, high-quality work with honesty and care.
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sb services
Rating: 5 out of 5
Extension Builder in Welwyn
We offer a range of high quality services, Extension, lofts and full or part renovations, plumbing and certified electrical work, we have gas safe engineers for anything gas related, kitchens and top quality carpentry work, bathroom installation and high end tiling, Flooring installation of all varieties (carpets, vinyl, tiles, wood) Whether it’s high end or a rental, we treat all jobs as if they are in our own home
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Latest review:
Kitchen Fitting- 25 Feb 2019
Scott fitted new kitchen, including new units, electrical sockets, new wall and floor tiles. He worked hard, on time, punctual, and on budget.

3.9

Top rated Extension Builders

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

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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.