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Luxury house extension builders

A family business with strong customer service values, Castle Oak’s house extension builders understand the importance of creating a bespoke extension that suits your unique needs. We deliver luxurious living, quality materials, comfort and exceptional service without compromise.

Beautiful, bespoke luxury extensions

Your happiness and satisfaction are our top priority at all times. Whether you’re looking for a small house extension for a home office or gym, or an expansive extension to maximise your living space, we promise the same attention to detail, and commitment to a first-rate finish, on every project.

Turnkey extension services

We’re more than just extension specialists or builders. At Castle Oak, we offer you everything you need in one comprehensive solution, with 100% professional support from inception to completion.

House extensions for any home

With qualified extension architects and over 70 years of combined construction experience, we design beautiful extensions to complement any style or size of property – anywhere in the UK.

Certified extension builders

For your peace of mind, all of our house extension builders are CSCS certified and we’re also NHBC registered – with the option to build under private license/building control if preferred.

Sustainable building solutions

We believe in responding to changing environments and demands. As a carbon-friendly company, we’ll design and build your new extension according to your required sustainability criteria.

    Planning and building your new extension


    We appreciate that any kind of building project can feel overwhelming, so we guide you through every stage of the process to ensure a seamless experience and truly immaculate end-result.

    • Free initial consultation and quotation
    • Architectural design and planning permission support
    • Source and supply of all materials – only of the highest quality
    • Complete extension build and project management
    • Snagging and client sign-off
    • Building control completion certificates

    We’ll keep in constant communication with you as your luxury extension project progresses, and are on hand to answer your questions at any time.
      Over the years, we’ve grown our business family to encompass established and well-respected artisans across a range of services to complement your house extension or building works:


      Dedicated to creating beautiful, functional and distinctive house extensions, our builders will not just meet your expectations, but exceed them.

      More than just extension builders…