Hartley Extensions builds single and double storey extensions, loft conversions, and full renovations across Surrey. Every project managed personally by founder James Hartley — same team, from planning permission to final handover.
From a single-storey rear extension to a whole-home renovation, every project is managed personally from planning application through to final handover.
Featured Project
Guildford, Surrey
A substantial rear and side-return extension to a 1930s semi-detached property. The brief was a seamless open-plan kitchen and living space, with bifold doors connecting directly to the rear garden. The result transformed how the family experiences the ground floor entirely.
Proudly building across Surrey
Working with Hartley was the best decision we made. They turned our cramped Victorian terrace into an open, light-filled home. The attention to detail is extraordinary.Mr & Mrs Pemberton, Weybridge
Our kitchen extension was completed on time and on budget. The team were clean, professional, and the quality is impeccable. We would not hesitate to use Hartley again.James H., Guildford
We have had three friends use Hartley since our loft conversion. That says everything you need to know about the quality of their work and the people behind it.Claire & Tom R., Dorking
Free site visit. No obligation.
We come to you, assess the property, and give you an honest view of what's possible and what it costs.
From the first call to the moment you move back in, you work with the same team throughout. No sub-contractors handed the job halfway through.
We visit the property, listen to what you want to achieve, and walk through what is feasible. No obligation, no pitch. Just an honest conversation about your home.
Our in-house design team produces drawings, handles the planning application, and manages all communication with the local authority. You approve every stage before we proceed.
A dedicated site manager oversees your project from day one. You receive weekly progress updates, and we are accessible by phone at any point throughout the build.
A final walkthrough with your project manager to sign off every detail before we hand over the keys. All guarantees, certificates, and documentation are provided on the day.
About Hartley
Hartley Extensions was founded in 2012 by James Hartley, a structural engineer who spent a decade working on commercial construction and decided there was a better way to build homes. The company is built around the belief that a homeowner deserves the same level of precision and communication that a commercial client expects.
Based in Guildford, we work across Surrey and the surrounding area. Over 120 projects later, the business is still run personally by James. Every client has his direct number, and he visits every site at least once a week throughout the build.
Many single-storey rear extensions fall under Permitted Development rights — no planning application needed. Larger or two-storey extensions typically require full planning permission. Hartley handles the entire planning process in-house, including all drawings and council communication.
A single-storey extension typically takes 10–16 weeks on site. Double-storey extensions run 16–24 weeks. Loft conversions average 8–12 weeks. Timelines cover structural work, first fix, plastering, second fix, and decoration — and are agreed in writing before the build starts.
Single-storey rear extensions typically start from £80,000. Double-storey extensions from £140,000. Loft conversions from £55,000. Every project is different — after the free site visit, Hartley provides a detailed fixed-price quote with no hidden costs.
Yes. Hartley does not subcontract mid-project. You work with the same team from groundworks to completion, with a dedicated site manager on site daily and James Hartley visiting every week. You have his direct number throughout.
Tell us about your home and what you want to change. We will come to you, take a proper look, and give you an honest view of what is possible.