How much
does a House
Extension cost?

When considering house extension costs, it’s essential to work with a local builder and architect for accurate quotes and the best results. As a trusted design and build company in Essex, we specialize in various types of extensions, including kitchen extensions, single-story extensions, double-story extensions, loft conversions, flat roof extensions, pitched roof extensions, and open-plan extensions. Each project is unique, with costs varying based on size and complexity.

All example costs:

All estimated costs for house extensions cover building work, architectural plans and planning submission.

All example costs:

All estimated costs for house extensions cover building work, plumbing, electrical work, glazing, external doors, architectural plans, structural engineering, and planning submission.

Detached House Extensions

Small Flat Roof Extension

Size 3m x 3m

Estimated costs:

£27,995+vat

Architectural Plans & Structural Engineering Included

Large Flat Roof Extension

Size 9m x 3m

Estimated costs:

£52,995+vat

Architectural Plans & Structural Engineering Included

Gabled Roof Extension

Size 4m x 6m

Estimated costs:

£49,995+vat

Architectural Plans & Structural Engineering Included

Pitched Roof Extension

Size 7m x 3m

Estimated costs:

£44,995+vat

Architectural Plans & Structural Engineering Included

Semi-Detached House Extensions

Small Flat Roof Extension

Size 4m x 3m

Estimated costs:

£29,995+vat

Architectural Plans & Structural Engineering Included

Large Flat Roof Extension

Size 8m x 3m

Estimated costs:

£49,995+vat

Architectural Plans & Structural Engineering Included

Gabled Roof Extension

Size 7m x 3m

Estimated costs:

£44,995+vat

Architectural Plans & Structural Engineering Included

Pitched Roof Extension

Size 5m x 3m

Estimated costs:

£34,995+vat

Architectural Plans & Structural Engineering Included

Terrace House Extensions

Small Flat Roof Extension

Size 3m x 3m

Estimated costs:

£28,995+vat

Architectural Plans & Structural Engineering Included

Large Flat Roof Extension

Size 6m x 4m

Estimated costs:

£50,995+vat

Architectural Plans & Structural Engineering Included

Gabled Roof Extension

Size 5m x 4m

Estimated costs:

£44,995+vat

Architectural Plans & Structural Engineering Included

Pitched Roof Extension

Size 6m x 3.5m

Estimated costs:

£43,995+vat

Architectural Plans & Structural Engineering Included

Bungalow House Extensions

Small Flat Roof Extension

Size 4m x 3.5m

Estimated costs:

£36,995+vat

Architectural Plans & Structural Engineering Included

Large Flat Roof Extension

Size 9m x 4.5m

Estimated costs:

£72,875+vat

Architectural Plans & Structural Engineering Included

Gabled Roof Extension

Size 6m x 4m

Estimated costs:

£54,775+vat

Architectural Plans & Structural Engineering Included

Pitched Roof Extension

Size 7.5m x 4m

Estimated costs:

£55,495+vat

Architectural Plans & Structural Engineering Included

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Our Google reviews speak for themselves

Zoe Hatcliff
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Another brilliant job completed. Thank you for never letting us down and completing within time frame. Won't hesitate to recommend you. Keep safe.
Vikki Thatcher
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Helpful and friendly. Top notch work at reasonable prices. Would definitely recommend
Sam Jarman
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Jamie and the team was great from start to finish. Would 100% recommend!
Arron Short
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Fantastic job, great guys and a very happy customer. Couldn't be happier with my single story extension would highly recommend
Gary Baker
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Jamie and the team at Kirkwood UK are professional punctual and extremely helpful 10/10 would recommend to anyone looking for a reliable builder
Olly Tait
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Jamie and his team were so profesional from start to finish and made the job a joy to watch our dream come together. Very knowledgeable and contactable throughout the process. Couldn't ask for a better outcome and value for money. Will definitely be recommending and 100% will use again! 5 star!!!
Ben Turner
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We used Kirkwood for our House Extension in Billericay, Essex. The project was managed by Jamie at Kirkwood and he took care of every step in the process. Kirkwood took care of the planning with their inhouse Architect, suggested a 3rd Party Building Control and right through to the build of the extension. This wasnt just an extension but a complete internal remodel. We are happy to recommend Kirkwood and in fact they have just completed a similar project at our neighbours house following our works.
Sandie
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I highly recommend the Kirkwood team! Exceptional workmanship, clear communication, Jamie & his team have provided the utmost as a polite & professional team! Very satisfied customer, looking forward to planning our loft conversion this year with you guys! Many thanks!
Andrew Morgan
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Fantastic service provided by Jamie and his team. Highly professional from start to finish, great communication with us throughout the project and wonderful attention to detail, making a tough project easier for us. Cannot recommend them highly enough.
Lindsay Alden
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A very professional company who listened to our thoughts and plans for our driveway and brought them to life. We have recommended them to friends who have also in turn recommended them to others, so their work speaks for itself. We are looking forward to Kirkwood transforming our back garden later this year.
Claire C
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Kirkwoods did a fantastic job if our garden after another company left us in the middle of the job with a building site for a garden. Jamie chatted through my plan with me and advised me regarding materials and the design. Their execution was exemplary as was their work ethic and reliability. I would not hesitate to recommend Kirkwoods to anyone.
Andrew Wiggins
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We’ve used Jamie and his kirkwood team for various construction work over the years. We have also seen them first hand on what they can offer their clients. Professional, punctual and quality of workmanship is second to none. We look forward to either working alongside them and when we need them using there services once again to help us with our ongoing projects.
Ellis Warwick
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Brilliant service throughout the whole project would definitely use again, Jamie spoke through all the plans and when completing the project it was done on time and to a very high standard
Frances Mulligan
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Really pleased with everything. All work done to a high standard and at a fair price. Will definitely be recommending 👍
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