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extension building experts

Extension Specialists Monmouth

Monmouth is a beautiful part of the world to live in, so if you’re in need of extra living space but don’t want to move away from the neighbourhood you’ve grown to love, then why not consider adding an extension to your property? If you want a modern, energy-efficient extension that blends in beautifully with the aesthetic of your home, then Thermotech is at your service.

Experts in all kinds of extensions

Ever dreamed of a larger kitchen, with beautiful bifold sliding doors that open out onto the spectacular Monmouthshire countryside? Then Thermotech can make your dream become a reality. However big or small your extension plans are, we have the skills and expertise to take on the work. We can build garage conversions, rear and side extensions, and we also fit kitchens. Even if you live in one of Monmouth’s iconic Georgian townhouses, and think you don’t have the room to extend, we can install a loft conversion to provide you with that much-needed extra living space.

Benefit from the best windows and doors that Monmouth has to offer

If you live in Monmouth or the surrounding areas, and you choose Thermotech to build your extension, you’ll also be getting the best quality windows and doors that are available in the South Wales area. All of the UPVC windows and doors that we install are A-rated as standard, so you can rest assured that adding extra living space to your home won’t send your heating bills soaring.

We guarantee a professional service

Thermotech is a family-run business, and customer satisfaction is important to us. Our team of friendly expert builders will work hard to ensure that work on your new extension is carried out both efficiently and professionally. What’s more, we will only use high-quality materials when building your extension, and we offer a 10-year guarantee on all works, so you’ll know that your new living space will look great for years to come.

Contact us

If you live in or around Monmouth, and are thinking of extending your home in the near future, then why not give the team at Thermotech a call on 0800 917 1106? Our friendly team is on hand to answer any questions you have. Or why not email us at with a few details about the sort of extension you’re looking for?


"From our first introduction to Thermotech through to the completion of the conservatory, our expectations were exceeded. From the foundation to installation the workmen were friendly, clean, polite and worked to a very high standard. My wife and I would recommend your company with confidence Thank you"

Mr and Mrs Evans, Rogerstone. conservatory installation

"The workmen were extremely conscientious, very clean and tidy when working. Very impressed with the quality of the products also. Our new front door exceeds our initial expectations. We would definitely use the company in the future and would recommend you to friends and family."

Mr and Mrs Body, Chepstow. New front door and window

"The whole process was excellent. The construction was very solid and well built with quality materials, especially the roof section and insulation which was magnificent. The workforce were also excellent especially your fitter with his superb skills. I can really recommend your services to anyone and would be happy to sing you and your companies praises"

Mr and Mrs Chapman, Magor. Solid roof sunroom

"Very pleased with the service provided by Thermotech. All workmen were friendly and Karl ensured their work was up to scratch throughout the process. Nothing negative to say- could not criticise and would definitely recommend and also use Thermotech again. Fantastic Job, great value for money and easy 10 out of 10 for overall experience."

Mr and Mrs Haddock, Blackwood Gwent. Conservatory installation

"We are delighted with our new conservatory. Karl managed the project and always responded quickly to any communications. The quality of the conservatory is excellent. Thank you Thermotech"

Mr and Mrs Morris, Caerwent Monmouthshire. Conservatory

"We are very happy with the excellent work involved in building our conservatory. Everything has been done to or satisfaction, quickly and efficiently. A job well done and we would have no hesitation in recommending the company in future."

Mr and Mrs Mitchel, Magor. Conservatory installation

"My wife and I would like to congratulate and thank you for erecting our conservatory to a very high standard indeed. Al workmen involved in the build were very polite, on time and worked extremely hard. Each and every member knew what was required of them to complete a first class conservatory. We are very pleased with the end result and would certainly recommend your company to others."

Mr and Mrs Edwards, Llangstone Newport, Conservatory installation

"Karl was very helpful and approachable throughout. All workmen involved in the installation were friendly and professional during the installation. Good after sales service when needed. Overall great company and would not hesitate to recommend or to use again. Already had many enjoyable and relaxing hours in the conservatory and look forward to many more."

Mr and Mrs Whittington, Shirenewton. Conservatory installation

"From the 1st telephone call asking for a quote to the fitting was like clockwork. Once order was excepted it was installed within 3 weeks. 1st class product, fitted by first class fitter by a first class company. Thanks."

Mr Wright, Chepstow

"Having seen the product at your showsite we knew what we wanted and the product fitted the bill in both quality and appearance. The installation of the door was carried out in an excellent manor, the fitters were extremely good, friendly and displayed excellent attention to detail. In conclusion, excellent product fitted by excellent staff"

Mr and Mrs Cramp, Tuthil Chepstow. Composite front door

Become our next satisfied customer

  • Expert Fitting Teams
  • 100% Satisfaction Record
  • Family Run Business
  • A Rated Windows as Standard
  • 10 Year Building Guarantee
  • Great Quality Products

Serving South Wales & the West

Based in Monmouthsire, we have been providing quality windows, doors, conservatories, roofs and building work all across South Wales and the West for over a decade. Come and visualise your home improvements by visiting our showroom in Chepstow.