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

1757 Results

Sort by:

LAS construction
No reviews yet
Extension Builder in Welwyn
A trusted construction company for building renovations, repairs and maintenance.
Get in touch
Ictinus Contractors
Rating: 4.9 out of 5
Extension Builder in Welwyn
Ictinus Contractors is a reliable London-based building and renovation team, delivering high-quality workmanship across residential and selected commercial projects. We specialise in painting and decorating, wallpapering, plastering and skimming, hard flooring installation, bathroom fitting, and general property improvements. We take pride in providing clean, well-organised work with strong attention to detail from start to finish. Whether the job is a single-room refresh, a bathroom upgrade, new flooring, or wider renovation work, our focus is always the same: quality finishes, honest communication, and dependable service. Based in East London, we cover surrounding areas across London and work closely with every client to make sure each project is completed to a high standard, on time, and with care.
Get in touch
Latest review:
Painting & Decorating- 6 Apr 2026
I had a very positive experience working with Konstantinos. He is personable, reliable, professional and excellent at co-operating throughout the process. He repainted my entire flat/walls/ceilings to a high standard (and sanded down) he also helped address a few additional repairs along the way. The finish is clean, fresh, and has completely transformed the space. He was thorough and ensured everything was completed properly and on time. I particularly appreciated his attention to detail and his proactive approach in taking care of things I hadn’t even noticed. I would happily recommend Konstantinos and would work with him again in the future! Thank you
Home Design & Build
Rating: 5 out of 5
Extension Builder in Welwyn
Tooled with years of experience, we undertake design & reconfiguration of builds; adding value to your home or business. Working closely with you; we create a bespoke, quality finish within your budget & affordability. Delivering a high standard of skill & integrity of craftsmanship we are proud off
Get in touch
Latest review:
Kitchen Fitting- 24 Jun 2025
Lalli and her team were all very professional, communicative, and detail oriented helping us create a new kitchen and bathroom that we love, not to mention, on schedule! We would highly recommend Home Design and Build and hope to work with then again in the future.
Yida Design and Construction Ltd
Rating: 5 out of 5
Extension Builder in Welwyn
Yida Construction is a limited company based in Central London. We are a very reliable and professional team of tradesmen with over 10 years of experience in the building industry, committed to delivering the highest levels of quality and service to our clients.
Get in touch
Latest review:
Restoration & Refurbishment- 26 Jun 2022
Tommy was a wonderful perfectionist and has done beautiful work in our stairway and hallway which had needed refurbishment for a very long time. It feels brand new. The flooring is perfect both in the hall and staircase, and the walls are now perfectly smooth and painted immaculately. Friendly and accommodating, we will be hiring again for more jobs in the future, undoubtedly. Thank you.
OWA CONSTRUCTION LTD
Rating: 4.9 out of 5
Extension Builder in Welwyn
We are a medium sized groundwork company based in West London. We have over 18 years groundwork experience. We specialise in Drainage , Basements Reinforced concrete, Foundations, Block and beam , Paving , Fencing Etc . We pride ourselves in our work and customer satisfaction is our top priority.
Get in touch
Latest review:
Groundwork & Foundations- 7 Feb 2026
Oli carried out the groundworks and demolition at my property and was on site every day with his crew, fully committed and hands-on throughout the job. I am an architect, and this was work on my own home, so my expectations were high. Oli met those expectations fully. He has a strong knowledge of groundworks and demolition, works carefully and methodically, and you can tell he genuinely enjoys what he does and takes real satisfaction in delivering the work exactly as required. He was always in a good mood, easy to communicate with, and a pleasure to have on site. I enjoyed discussing the project and hearing about other jobs he has completed over his 23 years of experience, which clearly shows in the quality of his work. I would highly recommend Oli for any groundworks or demolition works.
Rg building & landscape services ltd
No reviews yet
Extension Builder in Welwyn
Builder/landscaper Combined 35 years experience Trading standards approved Marshall’s registered installer FMB member Trust mark approved All building and landscaping works undertaken.
Get in touch
Friesian Group Ltd
No reviews yet
Extension Builder in Welwyn
We are a reliable construction and refurbishment company specialising in bathroom and washroom renovations, as well as all types of home repairs and refurbishment work. Our team delivers high-quality workmanship, attention to detail, and a professional service from start to finish. Whether you need a full washroom makeover or small repairs around your home, we are here to provide fast, trustworthy, and affordable solutions.
Get in touch
Badmoore Brickwork
Rating: 5 out of 5
Extension Builder in Welwyn
We are a small team of bricklayers with over 25 years experience working in the construction industry in and around Cambridgeshire and Hertfordshire. Our aim is to provide our clients with an outstanding level of service and an exceptional quality of workmanship. We pride ourselves on our reputation and ability to get the job right first time.
Get in touch
Latest review:
Bricklaying- 28 Feb 2021
Brilliant job by Craig - he had to correct poor work done by my previous builder, and i wish i had hired Craig straightaway........ work was done to a superb standard, and all finished very neatly, and measured properly so windows and doors fitted as they should. All mess was cleared up and left tidy, and they even left my mixer cleaner than when they arrived. Would certainly recommend, and will get them back if i need anymore brickwork, groundwork, patio, drive etc doing. Keep up the good work!!
Palmers air condition ltd
No reviews yet
Extension Builder in Welwyn
Construction
Get in touch
PROBUILTZ LTD
No reviews yet
Extension Builder in Welwyn
PROBUILTZ LTD is a reliable and experienced construction and property maintenance company based in London. With a skilled team of professional tradesmen, we specialise in delivering high-quality workmanship across both domestic and commercial projects. Our services cover everything from small repairs to full renovations, including: • Painting and decorating • Full property refurbishment • Bathroom and kitchen renovations • Flooring installation and repairs • Demolition and strip-out works • Partition walls and plasterboard installation • Plastering and ceiling repairs • Roofing – new installations and repairs • Extensions and structural alterations • Groundworks and drainage • Water and fire damage restoration • General property maintenance We take pride in being reliable, honest, and detail-focused. Every project is carried out to a high standard, ensuring clients receive long-lasting results and a professional service from start to finish.
Get in touch
Wolfwood Homes Ltd
No reviews yet
Extension Builder in Welwyn
I run a construction company that provides a services to both domestic and commercial clients. Our services range from initial site surveys including conditional surveys of existing properties, detailed design for both planning and building regulations, project management or main contractor service. We currently run projects that range from loft conversions and extensions through to completed builds, while at all times being customer focused with quality and safety as our priority.
Get in touch
Ecdl group ltd
No reviews yet
Extension Builder in Welwyn
From new builds to full renovations thats what we do. We design, we build we maintain.
Get in touch
Macbuild Construction ltd
No reviews yet
Extension Builder in Welwyn
Extensions, Loft conversion, renovation, electrical, Smart home control, automation, plumbing, heating and heating controls, networking, carpentry,
Get in touch
Comer Construction Services
No reviews yet
Extension Builder in Welwyn
I am a multi skilled builder, I set up Comer Construction Services 10 years ago and before that worked in my father's construction company for 10 years. I will take on work of all sizes from an extension that takes 18 months to fitting a laminate floor that is put down in a day.
Get in touch
Howe Structural Consultants Limited
No reviews yet
Extension Builder in Welwyn
At Howe Structural Consultant we provide drawings for residential internal alterations. Typically we will be called to site to carry out a full dimension survey and produce a set of drawings along with structural calculations for the alterations. The builder will then work from these drawings to meet the clients requirements. The calculations can be sent to the local authority for approval. We have over 10 years experience of design and drawings.
Get in touch
Nurend Rendering Specialists LTD
Rating: 4.9 out of 5
Extension Builder in Welwyn
NuRend limited have over 20 years experience in plastering and rendering between us , we are silicone render approved and issue ten year warranty small on silicone renders we also cover external wall insulation , damp proofing , floors screeds and much more . Look no further for any external works or internal works great communication polite and efficient Thanks again for reading Ellis Lockwood NuRend limited
Get in touch
Latest review:
Plastering- 13 Jul 2024
Thanks for your quote.

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.