By 321 Building Group

Bespoke Home Extensions across Bristol and the Surrounding Areas

At 321 Extensions, we take the guesswork, stress, and endless red tape out of transforming your home. Whether you are adding a modern kitchen-diner or a complete wrap-around extension, our streamlined 3-Step Process moves your project seamlessly from your initial ideas to a builder-ready structural specification.

We don’t believe in overcomplicating things. We operate under the industry-standard RIBA framework, meaning your project is backed by elite professional compliance, clear fixed pricing, and comprehensive insurance from day one.

How We Work with You:

  • Your Design, Your Choices: We tailor our service entirely around your lifestyle. Once your plans are approved by the council, you are completely free to use your own trusted contractor, or we can introduce you to our vetted panel of local, high-quality building firms to price up your build.
  • Total Transparency on Day One: We believe in absolute clarity. Our fixed design packages cover everything you need for planning and building regulations. To protect your budget, we outline all external council fees and third-party specialist requirements—such as independent Party Wall Surveyors—right at the start, so there are never any hidden surprises.

Meet the Director

Hi, I’m James Gillespie, founder of 321 Building Group.

With a BSc in Architecture and an MSc in Construction Project Management, I bring a rare blend of design precision and real-world construction logic to every home I touch. Before launching 321 Extensions, I spent 6 years as an architectural consultant at Winsor & Leaman Architects, where I personally delivered a massive range of residential projects—from complex home extensions and high-end luxury mansions to multi-unit accommodation schemes.

I built our 321 Countdown framework to fix a major industry flaw: bridging the gap between beautiful design and practical, on-site execution. I don’t just sketch layouts; I engineer fully constructible, council-approved packages that protect your budget, streamline your build, and make life seamless for your contractor.

Contact: mail@321buildinggroup.co.uk

321 Extensions is a 321 Building Group product.
©2026 321 Building Group. All rights reserved.
321 Extensions and 321 Building Group are trading names of James Gillespie.