Types of Oak

Not all oak is the same, and the type, cut and grade of oak used has a real effect on how an oak framed building looks, moves and lasts. As bespoke oak framing specialists serving Sussex, Surrey and Kent, we work with oak every day — this guide explains the main types of oak and grades you will come across when planning an oak framed project, so you know exactly what you are getting.

Green oak

Green oak is freshly sawn, unseasoned oak with a high moisture content. It is the traditional choice for oak framing because it is easier to work and cut joints in, and it is what we use for the vast majority of our frames. As green oak dries in place over the first months and years, it shrinks, settles and develops characterful surface checks (small cracks) and a silver-grey patina. This movement is entirely normal, expected, and has no effect on the strength of the frame — it is part of what gives oak buildings their character.

Air-dried and seasoned oak

Air-dried oak has been left to season, often for a year or more per inch of thickness, lowering its moisture content and reducing later movement. It costs more and takes longer to source, and is usually reserved for joinery such as doors, windows, staircases and internal features rather than the main structural frame, where a little movement is not a problem.

Oak grades and species

Structural grading

Structural oak is graded for strength and appearance. Characterful grades allow more knots, sapwood and natural features and suit a traditional look, while cleaner joinery grades are used where a smoother finish is wanted.

European vs English oak

Most structural framing oak in the UK is high-quality European oak, prized for its consistency and availability; English oak is often chosen for special features. We help you choose the right species, cut and grade for each part of your building.

Choosing the right oak for your project

The beauty of a bespoke oak building is that the right oak can be specified for each element — green oak for the structural frame, air-dried oak for fine joinery, and the grade chosen to suit the look you want. To understand more about why we build in oak, see why choose oak, and get in touch to discuss the right oak for your project.

Areas we cover

We are based in West Sussex near Crawley and work across Sussex, Surrey and Kent, including Horsham, Haywards Heath, East Grinstead, Crawley, Reigate, Sevenoaks, Tunbridge Wells, Guildford and the surrounding villages.

How oak is cut & used in framing

Beyond species and seasoning, the way oak is cut affects both strength and appearance. Beams are cut to make the most of the grain, and joints are formed with traditional pegged mortise-and-tenon connections rather than steel — the method that has kept oak buildings standing for centuries. We design each frame so the right size and grade of beam carries each load while showing the oak at its best.

Oak that weathers beautifully

Green oak needs no chemical treatment. Left natural it weathers gently to a silver-grey over the first few years, or it can be oiled to keep a warmer honey tone. Either way, an oak frame is virtually maintenance-free and only grows in character with age, which is why oak has been used for building in the South East for many hundreds of years.

What you get with Sussex Oak Structures

From your first enquiry to the finished frame, you work with one experienced, local team. We begin with a free consultation and scaled drawings of the whole structure, hand-cut the frame from sustainably sourced green oak in our workshop, and install it for you on site — this is a complete design-and-build service, not a flat-pack kit. We guide you through planning and building regulations where needed, and stand behind work that is built to last for generations.