Oak species guide
The oak we build with
English oak, green oak, seasoned oak, what the words mean, which species we use, and why oak has framed Britain's finest buildings for a thousand years.
In short
We build almost every frame from French green oak, European oak (Quercus robur) grown in France's managed forests, cut green and pegged by hand. It's dense, naturally durable and develops the characterful splits and silver-grey colour of a true heritage oak building.
'Green oak' refers to freshly sawn timber above 30% moisture, not a species. We cut it from English oak because it's easier and more affordable to joint by hand, and because its joints tighten as it dries. Where stability matters most, internal beams and fine joinery, we use air-dried (seasoned) oak instead.
The species
Which oak is which?
Three oaks you'll meet in timber framing, and where we use each one.
French green oak (European oak)
Quercus robur
France (our main source)
The classic framing oak. We source mainly from France's well-managed forests, where the slow-grown European oak is dense, straight and full of character, with deep grain and prominent medullary rays. It cuts cleanly green and seasons to a rich amber that weathers to silver-grey. This is the oak we use for almost every frame.
Used for
All structural oak frames, garages, garden rooms, gazebos, porches
Sessile oak
Quercus petraea
France, UK & Ireland
Closely related to European oak and often growing alongside it. Slightly finer-grained and straighter, it performs almost identically in framing. We use it where the timber's qualities suit the joint, occasionally drawn from the same French forests.
Used for
Structural frames and fine internal beams
American white oak
Quercus alba
North America
A different white oak group, paler and with a more even grain. It's not our default for green-oak framing, British and European Quercus robur has the superior character and provenance for heritage buildings, but we can use it for specific joinery on request.
Used for
Selected internal joinery and furniture, where specified
Green oak vs seasoned oak
Two routes from the same tree
Green oak and air-dried oak come from the same species, the difference is moisture. Here's how to choose.
Green oak
- • Freshly sawn, moisture content above 30%
- • Cuts and joints easily by hand, the traditional way
- • More affordable and widely available in large sections
- • Develops splits and silver-grey colour as it seasons in place
- • Joints tighten as the timber dries, often strengthening the frame
When we use it: Our default for garages, gazebos, porches and garden rooms
Air-dried (seasoned) oak
- • Dried over 1-3 years, moisture content 18-25%
- • More stable, far less movement after installation
- • Takes crisper, finer detail for internal joinery
- • Higher cost and longer lead time
- • Best where minimal movement and a settled look matter most
When we use it: Internal beams, fine joinery, extensions and restorations
Why oak
The properties that make oak the framing timber
Dense, durable, strong and a pleasure to work, here's what oak brings to a frame that other timbers don't.
Natural durability
Oak is classed as durable to very durable, its high tannin content resists rot and insect attack without treatment. Kept well detailed, a frame lasts well over a century.
Workability
Green oak cuts and joints beautifully by hand, the reason it became the framing timber of choice centuries ago. Mortises, tenons and pegs all go in clean.
Strength
A dense hardwood (around 720 kg/m³ seasoned), oak gives exceptional strength-to-section ratios, allowing generous spans on visible frames.
Movement
Green oak shrinks as it dries. We design for it, drawbored joints tighten, the frame beds in. Movement is a feature of the craft, not a flaw.
Sourcing & sustainability
Responsibly grown, fully traceable
Oak is a renewable building material when it's grown and harvested the right way.
FSC® certified
Our oak carries chain-of-custody traceability, so you know the timber came from responsibly managed forests.
French green oak
Most of our oak comes from France's well-managed forests, where slow-grown European oak (Quercus robur) offers the quality, grain and consistency that framing demands.
Low carbon, reusable
Oak stores carbon for the life of the building, over a century, and solid timber frames can be dismantled and reused, not demolished.
People also ask
Your oak species questions
Concise, snippet-ready answers to the questions buyers ask most about the oak in their building.
What is the best oak for framing?
French green oak, European oak (Quercus robur) grown in France, is the timber we favour for green-oak framing: dense, strong, naturally durable and a pleasure to cut and joint by hand.
What does 'green oak' mean?
Green oak is freshly sawn timber with a moisture content above 30%. It hasn't been dried, so it's easier to cut and joint, more affordable, and develops its characterful splits and silver-grey colour as it seasons in place.
Is oak a hardwood or softwood?
Oak is a hardwood, dense, strong and naturally durable. It's one of the strongest timbers used in British construction, which is why it's been the framing choice for centuries.
Will my oak frame rot?
No. Oak's high tannin content makes it naturally resistant to rot and insects. The only real threat is trapped moisture, which we design out with a sound roof and ventilated detailing.
Does oak need treating?
Generally no. Exterior oak is left to weather to silver-grey and resists rot unaided. Interior oak may be waxed or oiled to enhance the grain, but it's not required for durability.
Dig deeper
Frequently asked questions
A little more detail on the oak we build with.
We build almost every frame from French green oak, European oak (Quercus robur) sourced mainly from France's managed forests, with Sessile oak (Quercus petraea) used where its qualities suit the joint. Both are hardwoods proven in timber framing for centuries.
The craft behind the timber
Why Southern Oak builds the way we do
The specialists who cut your frame, and what sets our approach apart.
What makes Southern Oak different?
Every frame is cut and jointed by hand using traditional mortise and tenon joinery, no metal brackets, no shortcuts. We design each building around your home and plot, coordinate planning and building regulations with Planning By Design, and back our work with a 100+ year design life. It's heritage craft, delivered with modern project management.
Why choose Southern Oak?
Southern Oak coordinates the process from initial design and planning through specialist frame production and on-site installation. Planning support is provided with Planning By Design where required.
How are Southern Oak's buildings constructed?
Frames are produced from selected green oak using traditional mortise-and-tenon joints through Southern Oak's specialist sawmill partner in France. Experienced specialist installation teams then carry out the on-site work.
Keep reading
Related guides & buildings
Want oak you can trust?
Talk to us about sourcing, species and specification for your oak framed building.
Request your quote