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If you want an extension that feels as though it has always belonged to the house, an oak frame is often the starting point. Our oak frame extension kits give you a bespoke, precision-manufactured timber structure, designed from your own drawings to complement your existing home rather than compete with it. Whether you are planning a kitchen extension or a new living space, oak brings warmth, character, and a genuine structural presence, and homeowners across Cornwall choose it for its timeless appearance against stone, render, or brick.
At Cornish Frame Company, we design and manufacture every oak-framed extension from our workshop in mid-Cornwall, drawing on more than 30 years of experience in timber frame construction. Each package is supplied as a complete set of posts, beams, and structural elements, machined to shape and ready for assembly with minimal waste and disruption. We work closely with homeowners, architects and builders throughout Cornwall and the South West, from early design through to a weather-tight frame ready for the next stage of your build. Every project is manufactured to order, so no two frames leave our workshop exactly alike. |
What's Included in Our Oak Frame ExtensionEvery kit we supply is designed specifically for your project, cut and machined off-site in our workshop before delivery to your build. Nothing is templated. Every kit is manufactured from your own approved drawings, so each joint, beam and structural component is measured to fit your home precisely, with quality checked at every stage.
Your kit will typically include: ● Structural oak posts, beams and rafters, machined off-site to your design ● Traditional interlocking joints, engineered to distribute weight evenly across large or open-plan spaces ● Structural design and engineering calculations, ready for building control and local authority submission ● Detailed manufacturing drawings, so you, your builder or your architect know exactly what to expect ● Delivery to your build, with full installation available if you would rather we manage it for you An oak-framed extension generally covers the structural frame itself. Foundations, walls, roofing and glazing are usually arranged separately, either by your own builder or as part of our full installation service. We are happy to talk you through what is included before you commit to a design. |
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A Bespoke Oak Frame Extension for Any Kind of ProjectExtending a kitchen or living space, you're likely after something striking, built around how you actually use the room. Adding a garden room as part of a self-build, you're probably prioritising longevity instead: a structure that stands the test of time. An oak frame extension can deliver either.
As an architect or designer, you'll often specify oak as a feature within a larger renovation. As a developer, you can order a manufacture-only kit from us, engineered with minimal waste and ready to assemble on site. Owning a period or characterful property, you'll usually find an oak extension complements the original rather than competing with it. Whatever your starting point, get in touch and we're happy to talk through whether it suits your project. |
Benefits of an Oak Extension
Oak has been a trusted construction material in the UK for centuries, valued for its combination of strength, beauty and longevity in equal measure. Here is a summary of the benefits customers tell us matter most.
Timeless appearance - Oak's aesthetic appeal is genuinely timeless and sophisticated, suiting both traditional and contemporary properties.
Added home value - A well-designed oak extension can significantly increase a property's value and provide valuable extra living space.
Durability and low maintenance - Oak is naturally moisture-resistant and requires very little upkeep once installed and finished.
Sustainability - Our oak is sourced from sustainably managed forests, providing a natural structural material with a low carbon footprint and genuine sustainability credentials.
Thermal performance - Oak-frame structures offer excellent thermal performance and natural insulation, supporting energy efficiency.
Fast to assemble - Your frame is cut off-site, so it can often be assembled within days rather than weeks.
Design flexibility - Oak frames work well for kitchens, garden studios, orangeries and open-plan living spaces, adapting easily to your design.
Costs vary depending on the size of your extension and the complexity of the design. A simple garden sunroom will cost less than a large kitchen extension with vaulted ceilings and exposed beams, so we always start with an honest conversation about your budget and what you want to achieve. Choosing the right specification from the outset also supports cost-effectiveness over the life of the extension, since a well-specified oak frame requires very little ongoing maintenance.
Timeless appearance - Oak's aesthetic appeal is genuinely timeless and sophisticated, suiting both traditional and contemporary properties.
Added home value - A well-designed oak extension can significantly increase a property's value and provide valuable extra living space.
Durability and low maintenance - Oak is naturally moisture-resistant and requires very little upkeep once installed and finished.
Sustainability - Our oak is sourced from sustainably managed forests, providing a natural structural material with a low carbon footprint and genuine sustainability credentials.
Thermal performance - Oak-frame structures offer excellent thermal performance and natural insulation, supporting energy efficiency.
Fast to assemble - Your frame is cut off-site, so it can often be assembled within days rather than weeks.
Design flexibility - Oak frames work well for kitchens, garden studios, orangeries and open-plan living spaces, adapting easily to your design.
Costs vary depending on the size of your extension and the complexity of the design. A simple garden sunroom will cost less than a large kitchen extension with vaulted ceilings and exposed beams, so we always start with an honest conversation about your budget and what you want to achieve. Choosing the right specification from the outset also supports cost-effectiveness over the life of the extension, since a well-specified oak frame requires very little ongoing maintenance.
Start Designing Your ExtensionIf you are at the early stages of planning to extend your space, it is worth talking to us before your design is finalised. We can help shape a frame extension that fits your plot, your budget and the character of your property, so your plans and your build work together from the outset. Contact us on 07777 758367 or 07495 582664, email our team, or send a message through our enquiry form to arrange a no-obligation conversation.
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Our Process: From Design to DeliveryWe manufacture every oak-framed garden room kit to order, so no two projects are quite the same. Here is what you can expect when you work with us.
Because your frame is machined off-site, construction speed increases considerably compared with traditional construction methods. Many extensions reach the weather-tight stage within days of the frame arriving, though the exact timescale depends on the size, design complexity and access at your plot.
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Planning Permission, Permitted Development and Building Regulations
Planning permission requirements apply to oak-frame extensions in the same way as to any other extension. Many single-storey extensions fall under permitted development rules and may not require a planning application, provided the extension remains under 4 metres high and does not occupy more than half of the land around the original house. Larger or more visible oak extensions, particularly those on listed buildings or in conservation areas, are more likely to need planning permission from your local authority.
These rules can also require materials that closely match the existing property, which is one reason oak works so well as a considered choice for a period property. Building regulations apply to every oak-framed extension regardless of whether planning permission is needed, covering structural performance, insulation and energy efficiency from the outset, so your frame is manufactured to be compliant from the start. If you are unsure whether your project requires a formal application, contact us, and we can discuss your specific plans.
These rules can also require materials that closely match the existing property, which is one reason oak works so well as a considered choice for a period property. Building regulations apply to every oak-framed extension regardless of whether planning permission is needed, covering structural performance, insulation and energy efficiency from the outset, so your frame is manufactured to be compliant from the start. If you are unsure whether your project requires a formal application, contact us, and we can discuss your specific plans.
Designed to Suit Your Existing Building
An extension needs to work with the building it joins, not simply sit alongside it. We design each oak frame extension around your property's proportions, roofline and materials, so the result reads as a natural continuation of the house rather than an obvious addition. Exposed beams, vaulted ceilings and open-plan layouts are all achievable within an oak frame, and we can talk you through the options that suit your vision and your budget.
For homeowners seeking extra living space without losing the character of their property, an oak-frame extension is often an ideal solution. Whether you want to extend a kitchen or create a compact garden studio, for example, our team draws on decades of joinery expertise and structural know-how to create a frame that will stand for generations.
For homeowners seeking extra living space without losing the character of their property, an oak-frame extension is often an ideal solution. Whether you want to extend a kitchen or create a compact garden studio, for example, our team draws on decades of joinery expertise and structural know-how to create a frame that will stand for generations.
Areas we deliver to
Our oak frame kits are manufactured in Cornwall and delivered across the country.
We regularly deliver to:
We regularly deliver to:
- South West: Cornwall, Devon, Somerset, Dorset, and Wiltshire
- South East: Hampshire, Sussex, Surrey, Kent, and Berkshire
- Wales: South Wales and the West Wales coastline
- Midlands and North: Project-dependent, please get in touch for delivery costs
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faq'sWhat is included in an oak frame extension kit?
An oak frame extension kit includes the structural frame, manufactured according to your approved drawings. This covers oak posts, beams, rafters and traditional interlocking joints, along with structural engineering calculations. Foundations, walls, roofing and glazing are usually arranged separately, either by your own builder or as part of our full installation service. How long does it take to assemble an oak-framed extension?
Because every component is cut off-site, an oak-framed extension can often be assembled much more quickly than a traditional masonry extension, sometimes within days of the frame's arrival. Exact timescales depend on the size and complexity of your design, your access and the weather, so we will give you a realistic programme once we understand your project. Do I need planning permission for an oak extension?
It depends on the size, position and design of your oak extension. Many single-storey extensions are exempt from a formal application, provided they remain under 4 metres high and do not occupy more than half of the land around the house. Larger extensions, or those on listed buildings and in conservation areas, are more likely to need permission before work begins. We are happy to talk through your specific plot before you commit to a design. Will I need a planning application for a single-storey frame extension?
Many single-storey frame extensions do not need one, thanks to rules that cover most small-scale projects, so a formal application is not always required. This usually depends on the height of the extension, how much of the garden it covers and whether the materials match your existing property. If your site has specific restrictions, such as an Article 4 direction or listed building status, you are likely to need permission regardless of size. Do oak frame extension kits meet building regulations?
Yes. Every oak-framed extension we design and manufacture is engineered to meet current UK building regulations, covering structural performance, insulation and energy efficiency. These requirements apply whether or not your project needs planning permission, so we factor compliance into the design from the outset rather than treating it as an afterthought. Can oak frame kits be used for garden rooms?
Yes. Oak frame kits work well for garden rooms, home offices, standalone studio spaces, and extensions attached to the main house. A garden studio built around an oak frame gives you a versatile, characterful space that covers a wide range of uses, from a quiet home office to a garden studio. Can you match an oak frame extension to my existing property?
Yes, this is one of the most common requests we receive. We design each oak frame extension around the proportions, roofline and materials of your existing property, so the finished result looks like a natural continuation of the house rather than an obvious addition. If you have a period property or a building with particular character, we can discuss how to maintain that character in the new space. |
