Extension Builders in Welwyn

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

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Some of our top rated extension builders in Welwyn

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Volodymyr Girkovskyi
Rating: 4.7 out of 5
Extension Builder in Welwyn
I am responsible, I do my job carefully, I have extensive experience in building and renovating houses.
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Latest review:
Handyman- 9 Oct 2025
Good job, done as agreed
Emperor Contractors Limited
No reviews yet
Extension Builder in Welwyn
This is a construction company with many connections within the industry. Quality and longevity describes our state of works. We have a portfolio of many projects which all of them have been successful.
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Zen Construction
No reviews yet
Extension Builder in Welwyn
I’ve been working in the construction and property improvement industry for over 12 years, gaining hands-on experience across a range of jobs from full house renovations to smaller repair and maintenance projects. I’m based in London and cover surrounding areas. I specialise in Demolition, Carpentry, Bricklaying, Laminate Flooring, Extensions, Driveways, with a strong eye for detail, reliable workmanship, and a focus on delivering high-quality results. I take pride in being honest, hardworking, and easy to communicate with—clients know they can trust me to get the job done right the first time. If you’re looking for someone dependable, skilled, and committed to quality, I’m ready to help.
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Ed’s loft conversions Ltd
Rating: 5 out of 5
Extension Builder in Welwyn
We specialise in loft conversions, Extension to a complete house refurbishment.
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Latest review:
I engaged Edi to work on a full renovation and refurbishment of a 4 bedroom detached house with front and back gardens on Blackheath’s Cator Estate. Edi did an extensive amount of work, including stripping out; plumbing; plastering; windows installation; carpentry; and decoration. In addition, after commencing the property work, once the scaffold had been erected, following sensible advice, Edi and his team replaced the roof and fully insulated the attic; fitted additional electric points; rebuilt the garden patio; and replaced the flooring throughout, in addition to other important jobs including re rendering and pointing of chimneys, building new wardrobes in the main bedrooms; and upgrading the radiators. A new kitchen, and two new bathrooms have been fitted. The kitchen redesign meant knocking through a wall with the lounge to create a larger space. Edi is a highly skilled craftsman, who thinks creatively as he works to make best use of the space, including shelf fittings, and additional lighting for example. He has built some beautiful wardrobes, and the internal decorations have brightened up what was previously a rather shabby looking house. In addition to the above, I wish to commend Edi for his professionalism, courtesy, and passion for doing the best work possible. On all the site visits I attended, and every time I spoke with him on the phone, it was striking how much he cared about the work that he was doing, his desire to ensure that the house would look the best. I always left site visits with the feeling that he cared so much about the house that he could be safely relied on to give the best advice to enable us to make the right decisions. I also noticed that Edi and his team would take the upmost care to keep the property safe, tidy and in good shape throughout the project. He can be fully trusted to look after any site he works on. He is intelligent and careful when it comes to safety and security. It has been a pleasure for Edi and his team to work with us over a period of around 6 months, and he did so much to reduce the stress of a significant project so that we could always rely on him to work methodically, patiently and sensibly, and to make best use of the resources available. His pleasantness shines through, and everyone I know who has spoken to him has always provided me with the most positive feedback I have no hesitation in recommending Edi to anyone who wishes to engage him for future projects, and is most deserving of the good words that I and others that work with him have to say about him.
Badesha builder ltd
Rating: 1 out of 5
Extension Builder in Welwyn
I am running a company badeshabuilder ltd. I have hard worker people working for me, whose have 12 year experience in builder work. We doing all extensions, bathrooms, kitchen, loft and all kind of building work. Please take a look of photos of previous work. Thanks for reading.
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Latest review:
Plastering- 18 Mar 2021
Guy came down to quote and I've subsequently text him as to when he can start and 2 days no answer. Gave the job to someone else. Not professional at all!!!
Lita construction ltd
Rating: 4.7 out of 5
Extension Builder in Welwyn
All kinds of work,Framework,Basments,groundworks, refurbishment, extension,lots years experience in this field predominantly working on housing developments of different sizes.
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Latest review:
Groundwork & Foundations- 1 Apr 2024
Concrete job
House2Home
Rating: 5 out of 5
Extension Builder in Welwyn
House to Home Atelier is a local building company based in Abbey Wood, South East London. We specialise in end-to-end home renovations and construction, from initial design and planning to final finishes. Our team delivers loft conversions, house extensions, full refurbishments, bathrooms, kitchens, and bespoke interior solutions, always with a focus on quality, efficiency, and maximising space. We combine traditional craftsmanship with modern solutions, ensuring every project is completed on time, on budget, and to the highest standards. With our experience and carefully selected team of skilled tradespeople, we take care of everything from structural work and plumbing to carpentry, plastering, and finishing touches. We are local, accountable, and hands-on, so you always know who is managing your project. Your home is your investment, and we treat it as our own. Whether it’s a small repair or a full-scale renovation, we deliver solutions that maximise space, enhance character, and provide lasting quality.
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Latest review:
Works consisted of hip to gable loft conversion under permitted development and a refurbishment of the first floor of a semi-detached house into a four bedroom/bathroom layout, including new windows, balconies, wiring and plumbing as well as sound proofing the walls. With 100m2 of works this was my first introduction to a major building project and I was worried by the horror stories I have heard about builders. From the outset Monika set my mind at rest, listening to what I wanted, making helpful suggestions, offering tips for instance on how to save on the scaffolding and always asking me when choices needed to be made. She took the trouble to ensure that I knew what was happening, with daily photos of progress without the need for me to climb scaffolding. I was working to a tight timescale and budget, which Monika understood, and even having accommodated a number of changes including some additions, the project came in on time and on budget. All of the workers on the site were very professional and the quality of the work and the attention to detail was exceptional. I have no hesitation in recommending Monika and her team - I went into this project apprehensive and not sure what to expect; thanks to Monika, I came out the other side delighted by and looking forward to working with her and her team again to renovate my ground floor.
CPR (Complete Property Renovations)
No reviews yet
Extension Builder in Welwyn
CPR (Complete Property Renovations) is a professional property renovation company specializing in complete renovation solutions for residential and commercial properties. We deliver high-quality workmanship across every stage of the renovation process, from initial demolition and structural alterations to the final finishing touches. Our services include kitchen and bathroom renovations, flooring installation, painting and decorating, electrical and plumbing works, interior refurbishment, and complete property fit-outs. Whether you’re renovating a house, apartment, office, or retail space, we are committed to delivering reliable, efficient, and high-quality results tailored to your needs.
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Elite plumbing and heating
Rating: 5 out of 5
Extension Builder in Welwyn
We do quality work, at reasonable price
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Latest review:
Bathroom Fitting- 15 Nov 2023
Sandeep is very good and finish the job within the time he given and always answer the call. Work done better then my explanation and also clean everything after finish the work.
BWH Construction
No reviews yet
Extension Builder in Welwyn
Hi my name is Brian, I have been working in the construction industry for over 20 years, in this time i have worked with various big companies on projects from the Channel tunnel, to demolishing houses digging basements then rebuilding. References available upon request
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RSL Renovation Ltd
No reviews yet
Extension Builder in Welwyn
We are a trusted and experienced general contracting company, delivering high-quality craftsmanship across all areas of construction, extensions, alterations, and refurbishments. With a commitment to excellence and attention to detail, we bring your vision to life— on time and within budget. Our Services Include: • General Building – Full refurbishments and renovations tailored to your needs • Extensions & Loft Conversions – Expertly designed to enhance space and value • Bathroom & Kitchen Installations – Stylish, functional, and built to last • Floor & Wall Tiling – Precision tiling for a flawless finish • Carpentry & Joinery – Custom woodwork and structural solutions • Plumbing & Electrical Work – Safe, certified, and up to code • Interior & Exterior Decorating – Transforming spaces inside and out • Garden Landscaping, Fencing & Paving – Creating beautiful and practical outdoor areas • Maintenance Services – Reliable upkeep for homes and businesses Whether it’s a complete renovation or a small upgrade, we approach every project with professionalism and pride.
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P&K Construction
No reviews yet
Extension Builder in Welwyn
We are on UK construction market from 20 years, usually we do loft conversions, extensions and new build houses. We can also deal with bathrooms, kitchens, decoration, roofing all aspects of building works.
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Ultra renovations
No reviews yet
Extension Builder in Welwyn
I’m a multi-skilled builder with hands-on experience across carpentry, joinery, plastering, tiling, and general construction. I take pride in delivering quality workmanship, problem-solving on site, and finishing jobs to a high standard
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Ma bespoke driveways
No reviews yet
Extension Builder in Welwyn
Essex herts north Essex
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Mario Services
Rating: 5 out of 5
Extension Builder in Welwyn
Mario & Alex Construction LTD specialise in construction and building services, complete property refurbishment, house extensions and loft conversions. Provides unmatched customer service. Our commitment to small,hudge integrity, providing the highest value and satisfied customers, has been the ingredient that has fueled our growth from the beginning. We ensure that all our work is professionally managed so that the result is of outstanding quality, cost-effective.
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Latest review:
Bathroom Fitting- 20 Jan 2023
We highly recommend Mario & his team. They fitted a new kitchen & bathroom to a really high standard within a short, timeframe. They work hard, are friendly, professional & honest, my neighbour even commented on how considerate they were! Upon first meeting Mario we were impressed by how organised he was. He arrived on time with the description we’d posted on my builder & went through it methodically. We had A LOT of questions! He answered all of them & didn’t rush us. We received a competitive quote within a day as promised. It included everything we discussed & he quickly answered our follow up questions. We wanted an accurate idea of the cost of electrical work & Mario arranged for his electrician to come & inspect/quote before we’d appointed Mario the job. Our kitchen & bathroom is complicated, with lots of difficult angles. Damp, unlevel floor, unlevel windows, a low ceiling were uncovered in the bathroom. Mario did well to identify solutions, giving us expert advice. Pipes were neatly chased into the wall. Underfloor heating & LVT, tiling, grouting & painting all done to a very professional finish. He kept us informed of progress, checked our preferences & was patient when we had supply delays, finding ways to ensure the job finished on time enabling us to move from our temporary accommodation back home in time for Christmas. He promptly fixed some minor issues after the job finished. We highly recommend Mario & would use him again.
Balham construction Ltd
Rating: 5 out of 5
Extension Builder in Welwyn
Balham construction are a London based refurbishment and construction company that offer a wide range of services from full Property refurbishment to extensions and loft conversions and everything in between
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Latest review:
Tom and the team completed a full renovation of my flat. This included refurbishment of my kitchen, bathroom and general redecoration. The team were extremely hardworking and punctual and no job was too difficult for them. I would highly recommend their services.

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.

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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.