21st Century Design & Build Ltd
Extension Specialists. 21st Century Design & Build Ltd has been vetted and approved by TrustATrader. Covering Throughout London
Membership number TT28757
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Register GuaranteeAbout 21st Century Design & Build Ltd, London
About Us
21st Century Design & Build Ltd is a London-based design and build specialist offering high-quality house and bungalow extensions across London and the surrounding areas. With over 15 years' experience in home extensions, loft and garage conversions and new builds, we help homeowners unlock the untapped potential in their properties without the cost and disruption of moving. Our approach combines practical design, careful project management and skilled craftsmanship to deliver long-lasting, compliant and value-enhancing results.
Why choose us
- Over 15 years' experience delivering house and bungalow extensions across London and neighbouring boroughs
- Full design & build service tailored to your vision, budget and property
- Expert advice on space use, planning requirements and building regulations compliance
- Free, no-obligation quotes and clear, transparent estimates
- Skilled in all aspects of interior and exterior finishes to ensure a seamless end result
Services offered
- House Extensions
- Bungalow Extensions
- Loft Conversions
- Garage Conversions
- New Builds
- Roofs
- Kitchen Fitting
- Bathroom Fitting
- Windows & Conservatories
- Decorating & Renovations
- Carpentry & Joinery
- Plastering & Finishing
- Surveying & Planning
- Plumbing & Heating
- Drawings & Plans
- Building Regulations
- General Building Work
We pride ourselves on professional communication, reliable project delivery and attention to detail from initial survey and planning through to completion. If you would like to discuss your project or request a free quote our advisers are happy to help. Please mention TrustATrader when calling.
Photo gallery
Extension Projects
18 photos
Work in Progress
59 photos
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21st Century Design & Build Ltd
- Identification checked
- Company address verified
- Customer references checked
- Agreed to TrustATrader's high standards
- Agreed to complaints procedure
Insurance details
| Provider | QBE |
|---|---|
| Verified | 23rd December 2025 |
Qualifications
- Logic Certification for Working Practices in Energy and Utilities
Associations
Reviews (24)
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Average rating: 5.0 out of 5
Review by Patrick Ward
on 18th March 2026
"This is the second time using the 21st century and design and build team and couldn’t be happier! This project was twice the size of the last one and the team really delivered, even with some notable unforeseen challenges along the way they managed to bring the build in on time and on budget! Their knowledge and experience really shone through when finding solutions during the build, the whole team were friendly and worked hard. A special thank you to Tom who was our main point on contact during the build and made everything run smoothly. Would highly recommend!!"
- Initial impression Initial impression: 5 out of 5.0
- Punctuality Punctuality: 5 out of 5.0
- Cleanliness Cleanliness: 5 out of 5.0
- Quality Quality: 5 out of 5.0
- Value Value: 5 out of 5.0
- Overall opinion Overall opinion: 5 out of 5.0
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Average rating: 5.0 out of 5
Review by Clody
on 1st February 2026
"We have had a great experience with Thomas and his team. Thomas really helped us with a complete kitchen renovation. He opened up the back of our house, had to relay our sub-floor and fixed a complicated damp problem. Thomas and Clay provided us with excellent advice and were delightful to have in the house. Their attention to detail and ability to manage a complex project is very impressive. They went over and above at every stage and I’d happily work with them again."
- Initial impression Initial impression: 5 out of 5.0
- Punctuality Punctuality: 5 out of 5.0
- Cleanliness Cleanliness: 5 out of 5.0
- Quality Quality: 5 out of 5.0
- Value Value: 5 out of 5.0
- Overall opinion Overall opinion: 5 out of 5.0
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Average rating: 4.67 out of 5
Review by Ed Scott
on 24th October 2025
"Tom and the team were really helpful, when anything unexpected occurred they ensured to gather all the information to make decision making much easier."
- Initial impression Initial impression: 5 out of 5.0
- Punctuality Punctuality: 4 out of 5.0
- Cleanliness Cleanliness: 5 out of 5.0
- Quality Quality: 5 out of 5.0
- Value Value: 5 out of 5.0
- Overall opinion Overall opinion: 4 out of 5.0
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Average rating: 5.0 out of 5
Review by Mike
on 2nd October 2025
Mike - Image 1 "Thomas and his team renovated the whole of my property. Kitchen, bathroom, bedrooms, living room and hallway. They have done a fantastic job. From start to finish Thomas has been highly professional. From giving advice, keeping me up to date with progress reports, and delivering a top class job. I could not recommend more highly."
- Initial impression Initial impression: 5 out of 5.0
- Punctuality Punctuality: 5 out of 5.0
- Cleanliness Cleanliness: 5 out of 5.0
- Quality Quality: 5 out of 5.0
- Value Value: 5 out of 5.0
- Overall opinion Overall opinion: 5 out of 5.0
