Oak framing – a building technique whereby oak is used to form the primary load-bearing structural skeleton of a house – has been around for centuries. Thanks to the material’s innate strength and the versatility of oak systems, this construction technique remains a firm favourite with the UK’s self-builders.
The option to leave parts of the frame exposed, whether on the interior or exterior of your house, means your oak frame can double up as an architectural feature, too – few construction materials can deliver the array of warm, honey-coloured hues or distinctive splits and shakes that oak can.
Oak is also versatile, and can be woven into projects of all scopes, from new builds and extensions to conversions and restoration projects where a new structural skeleton is required to support the existing building. Here, we take a closer look at the many advantages of oak frame as a building system, exploring how it stacks up against other options when it comes to meeting 21st century living requirements.
Article continues belowTypes of oak frame
You have several options for your oak frame, which can contribute to either a modern or traditional finish. This is largely led by your choice of hidden or exposed frame.
The principal characteristic of an exposed oak frame is that the oak is (usually) exposed both internally and externally. Internally, the principal walls, floor joists, trusses and roof members can all be visible. Between the exposed oak timbers are the render panels. These consist of extremely thermally-efficient foam panels fixed to board and set within the panel timbers.
Hidden oak frame houses are usually based on a heavy oak frame, although it could be Douglas fir, and they invariably have a more open feel to the structure. They are a perfect match for large glazed areas.
External finishes can be a combination of infill panel insulation, external cladding and large scale glazing. Fully vaulted roofs are a feature of this design creating a spacious feel. A major attraction of this style is the flexibility it allows in design and usage.
14 things to know about oak frame homes
1. Oak frames offer design flexibility
In many ways, oak delivers the best of both worlds: a robust and practical structural system that will stand the test of time, as well as a premium building material that oozes endless character and style.
"It supports long spans, open plans, double-height spaces and feature ceilings," says Daniel Wilson, design and project consultant at Carpenter Oak. "Exposed pegged mortice and tenon joints and large timber elements lend an unmistakable sense of craft and authenticity that many self-builders value."
Daniel is an experienced Architectural Designer at Carpenter Oak, and has many years of experience working within a range of contractors across the self-build timber framing industry.
2. Rural locations work well, but suburban settings can work too
Thanks to the handcrafted look and feel of oak, houses and extensions with an oak frame sit beautifully in rural settings.
"Oak frame homes work well in rural and edge-of-town/village locations, where natural materials sit comfortably within the landscape, and planning authorities often welcome traditional construction methods with contemporary interpretation," says Daniel Wilson.
Having said that, contemporary oak frame properties sit well in suburban settings, too, when designed with modern architectural glazing and finished in materials that complement the local vernacular.
3. Traditional and contemporary builds are possible
The concept that a structural oak frame only suits houses finished in a traditional style is probably one of the biggest self-build myths out there. Numerous aesthetics are achievable, depending on the house’s location and the look you want to create, whether that’s a traditional barn-style dwelling or a modern house with broad spans of glazing.
Timber cladding, render and brick outer skins all pair well with the oak structural skeleton, which means you can curate pretty much any look you like.
"The style of home or oak frame extension you’re looking to achieve will largely dictate how much oak is required. Traditional styles generally require the most amount of oak, usually exposed both internally and externally," says Gareth Edmunds, director at Welsh Oak Frame. "Post and beam layouts work on a simple grid system and require even less oak. This style perfectly suits modern home designs and open-plan spaces."
Gareth Edmunds is a director at Welsh Oak Frame, a company that supplies oak frame structures for all types of homes, conversions and extensions.
4. The design flexibility is vast
The list of design possibilities when building with an oak frame is almost endless – one of the reasons this method remains so popular with self-builders. "An oak frame isn’t limited to any particular form; it can support classic proportions or bold modern geometries," says Daniel Wilson.
The beams are typically connected via traditional mortise and tenon joints, with pegs that hold everything together. A wide range of layouts is possible thanks to the generous size of the timber beams, allowing for open-plan living with wide spans and minimal internal supports.
"Oak can achieve vaulted ceilings, mezzanines and dramatic roofscapes, as well as large, glazed facades," says Daniel. Plus, as the timber can be left exposed internally, oak offers a golden opportunity to create a characterful design focal point, which can be finished and treated according to the homeowner’s taste.
5. But, design constraints need to be considered from the start
The beams, trusses and posts that form the oak skeleton are an inherent part of your house’s structure. Therefore, oak frame homes work best when the structural bays and trusses are factored into the design from the outset.
"How rooms are divided needs to be considered early on as part of the design process so they don’t clash with the structural grid," says Daniel Wilson. Long, unsupported spans of greater than 5m are possible, but may require the use of additional posts or steel supports, as well as additional detailing – both of which can add to costs.
Thermal and moisture integration present further factors to consider during the design phase. "Exposed timber needs careful detailing at interfaces – windows, roofs, floors – to ensure airtightness and avoid thermal bridges,’ says Daniel.
6. Oak frames will change over time
Many oak frame homes in the UK are built using newly felled timber, known as green oak. This wood comes with a higher moisture content that makes it easier to work with and means the oak will naturally dry out and shrink over time.
Yet, this natural process doesn’t weaken the structure. "In fact, the opposite happens," says Gareth Edmunds. "As the oak shrinks and splits over time, the joints get stronger making your house sturdy and full of character."
What’s important is to choose a supplier who understands how the material contracts over the years and can factor this into the detailed design.
There is debate regarding whether it’s better to use green oak for building an oak frame home, or seasoned oak that’s been pre-dried. According to Gareth, it’s a myth that the latter is better for building. "It’s better to use green oak when constructing oak frame buildings," he says. “The moisture content tends to be a lot higher than air-dried oak. Therefore, it makes it softer and easier to cut and shape into exact sizes."
7. Insulation and energy performance needs to be considered
Historically, an oak skeleton would have been wrapped in wattle and daub or brick to create the structural envelope. Today, high-quality infill panels or encapsulation systems are used to fill in/wrap the oak frame and ensure top-notch thermal performance.
For many self-builders, structural insulated panels (SIPs) are a popular choice of encapsulation system. Each panel comprises two layers of OSB, sandwiching an inner layer of rigid insulation. Like the oak frame, SIPs are manufactured off-site, guaranteeing a highly efficient, pre-determined level of thermal performance once erected on site.
Some suppliers, such as Oakwrights, offer their own line of wraparound panels, providing equally impressive thermal performance. "Our ultimate panel is the WrightWall & WrightRoof Natural panel, which is filled with the highly respected Steico-Zell wood fibre insulation," says Sam Grew, an architectural technician and Passive House consultant at Oakwrights.
This option is available in varying thicknesses depending on the desired performance levels and structural requirements. "Alternatively, our high-performance panel WrightWall and WrightRoof pre-insulated panel system uses rockwool insulation, lined with thick rigid insulation to mitigate cold bridging," says Sam. "These panels easily attain exceptional levels of thermal efficiency and airtightness."
Sam works at Oakwrights, helping to produce building regulation drawings to ensure Oakwrights bespoke projects meet and exceed the requirements for building regulation standards.
8. Passivhaus certification can be achieved with an oak frame
Passivhaus certification is possible with an oak frame, providing this goal is factored into your plans from the start of the process, so your architect and oak frame supplier can map out a design that meets the rigorous standards Passivhaus certification requires.
"Whilst designing a certified Passivhaus, we produce a PHPP model (Passivhaus Planning Package) detailing the performance of the materials, heating specification, window details and much more, all to calculate whether it meets the strict conditions," says Sam Grew.
For instance, on a Passivhaus-certified Oakwrights home in Worcestershire, the company’s WrightWall and WrightRoof Natural panel system were used to establish the thermal shell of the dwelling. "Infilled vaulted ceilings, shading or cladding using the balconies and shades, triple glazing and ground source heat pump and MVHR all work with the thermally efficient and airtight building envelope to meet certification requirements," explains Sam.
9. Using a specialist designer will give the best results
You don't always have to work with an oak frame designer, but working with a specialist typically yields the best results. That said, the main routes to designing an oak frame home are:
- Have an independent architect create a set of plans. These can be taken to your oak frame supplier, who will adapt them into specialist technical drawings.
- The second route is to work with your supplier’s in-house design team on a bespoke plan.
- Choose a design from your supplier’s portfolio of off-the-shelf houses and adapt it to your taste.
"Timber framing has nuances that benefit from specialist input: structural joinery logic, engineered connections, optimal bay planning, integration with insulation and fabric performance and on-site erection sequencing," says Daniel Wilson.
"When a specialist oak frame designer works alongside an architect from the concept stage, the entire design becomes holistic – structure, space and performance are considered together, reducing surprises later in detailing, cost planning and construction."
10. Self-build mortgages are possible for oak frame homes
Another myth that’s perpetuated in the self-build world is the idea that it’s harder to get a mortgage for a self-built, oak frame home.
"The myth that timber build systems aren’t mortgageable has come about because of self-builders not following lenders’ rules regarding features like cladding," says Gareth Edmunds. "Lenders will set out a range of criteria informing things such as cladding choice and roof type, which must be adhered to if you are to successfully obtain a self-build mortgage from them."
According to Gareth, these rules apply to all building systems – not just those that are timber based. "All lenders have different criteria and some are stricter than others, so it’s worth doing your research."
11. The build process is different to other systems
Once the technical drawings for your oak frame are finalised, they’ll be sent to your supplier so they can fabricate the structural components in their workshop. During this time, you can appoint your own builder to carry out preparatory groundworks on site.
Once the frame is complete, it is delivered to your site and typically erected by your oak frame supplier’s in-house team. Then, with the frame up, the encapsulation system can be installed, leaving you with a weathertight shell. This allows trades to begin work internally, while finishing materials are added to the outside of the house simultaneously.
Depending on the size and design of the house, the whole process can take between 18 and 50 weeks.
12. You may still need to bring in other trades
Outside of your oak frame supplier, you’ll need to engage a builder/groundworks team to install the foundations prior to the arrival of your oak frame. Accuracy at this phase of the project is crucial, so the pre-manufactured frame sits perfectly on top of the base, right down to the last millimetre.
Once you reach wind and watertight stage (ie the oak superstructure assembled on site and the encapsulation system/infill panels installed) you can either appoint a general builder to complete the project, or engage individual trades to take care of the roofing, external façade, doors windows, services and interior fixtures and fittings.
13. Oak frame costs may be more, but can be manageable
Oak is widely considered to be a premium building material – but that doesn’t mean you need a bottomless budget to create an oak frame abode.
For instance, choosing rectangular bay floorplans and modest glazing can help minimise oak frame costs. "The higher the volume of oak, the higher the price will be," says Gareth Edmunds. "However, if you were to go for a more simple, post and beam style oak frame, where elements such as rafters are made of softwood and hidden behind the walls, then it’ll be less expensive," he notes. You can also claw back cash by taking on certain tasks, such as project management and sourcing follow-on trades, yourself (rather than using your oak frame supplier).
14. Oak framing can be sustainable
Providing you choose a supplier that can prove their oak is sourced from a responsibly managed forest with a robust replanting scheme in place, there’s no reason why your oak frame project can’t be sustainable.
"As a structural material, oak aligns with the growing demand for sustainable and durable building solutions," says Charlie Mills, managing director at Oakwrights. "Clients are pleased to be reducing their reliance on steel and concrete, choosing instead a natural, long-lasting material with a significantly lower environmental impact."
Oakwrights, for instance, has sourced its oak from family-run forests for the last 25 years. "Primarily in France, these forests adhere to strict environmental, social and ecological standards to protect biodiversity," says Charlie.
Reputable oak framers employ highly accurate, computer-controlled processes to engineer each building component, so each piece of your oak frame is manufactured to the nearest millimetre, minimising any waste.
"At Oakwrights, we purposefully use the heartwood of the tree – the hardiest section of the trunk – to create our frames," says Charlie. "Unlike other materials that may gradually deteriorate, green oak’s versatility allows frames to be crafted to exact requirements, and it continues to strengthen with minimal maintenance once erected."
FAQs
What are the pros and cons of oak frame homes?
Pros:
- Oak is naturally resistant to insect and fungal attack
- Impervious to weather
- Virtually maintenance free
- Increases in beauty and strength with age
- Can be sustainably sourced
- Work well on sloping sites
Cons:
- Requirement to design around beams
- Limit to room's open depth without encountering a post of around 4.5m
Can you build an oak frame on a budget?
Post and beam homes in other countries rarely use oak. In North America, they usually use Douglas fir or some other softwood species, and there is no reason why you can’t use something cheaper than oak.
Where oak really comes into its own is in large open plan spaces, especially ones with vaulted ceilings. There is nothing to stop you going for a conventionally built home and adding an oak framed extension, enabling you to get the ‘wow factor’ for less.
Can I add other eco-elements to an oak frame?
Yes, you can add other elements such as renewable energy to an oak frame. You could integrate solar panels to produce hot water and/or electricity, or consider installing a heat pump which operates well with low-heat-demand heating systems such as underfloor heating.
Does oak frame shrink?
Yes, during its first few years, oak shrinks by as much as 5% radially (that is across the grain), but the length of each piece remains the same. If you work with a good designer, they will this into consideration when putting frames together, so it's no cause for concern.
However, when detailing the joints connecting the posts and beams, the shrinkage factor is used to make the joints tight. The pegs used to fix the joints are always tapered and the holes between the timber are normally offset, allowing the shrinkage to gradually draw them into a strong alignment over time.
Another area where shrinkage is a factor is glazing and joinery. Oak builders have become adept at designing weatherproofing details which can cope with a backing frame which is set to shrink.
Does it have a greater fire risk?
No. Structural timber is, in fact, not quick to burn. Research shows that fire fighters would rather enter a timber frame building on fire as timber has a known and predictable burn and char rate. Plus, it is not explosive.
All timber frames commercially available have to be manufactured and erected in accordance with all regulations and warranties. Lenders and insurance companies do not differentiate between timber frame and masonry construction.
How do I choose a supplier?
All oak framed housebuilders offer a bespoke service. Some are very small, little more than one-man bands, whilst others are now well established as design and build businesses, catering mostly to the self build market.
If you have decided that an oak frame house is for you, what should you be looking for when it comes to choosing a supplier?
- Look for a company that can produce the type of home you want, by looking at their brochures and website
- Try and visit their finished houses in person
- Check the company is reputable with a solid trading history
- Find out what the payment terms are. How much will you need to pay as an upfront deposit? How will your money be held?
- Choose a company with plenty of experience of building timber frame post and beam and working with self builders
- It is essential that you get on well with them and they have an understanding of your project
For more inspiration on building with an oak frame, check out these oak frame conservatory ideas and find out how this homeowner created a future-proof oak frame home.
