Okan is a tropical hardwood that naturally belongs to durability class 1 — the highest category in the European standard EN 350. The wood is supplied fine-sawn, is extremely strong and is naturally resistant to rot and insects, without any treatment. This makes Okan suitable for permanent ground contact (use class EN 335 GK4), which makes it a logical choice for posts, load-bearing beams and structures that stand directly in the ground. The wood is TLV-certified and available in lengths up to 5 metres. At Houthandel Jan Sok in Meppel — founded in 2009, KvK 04062841, average 4.8 stars from more than 141 reviews — we sell Okan posts, beams and planks to private customers, sole traders and contractors from the same range. In this article you will read what Okan is, what properties it has, what you use it for and how to maintain it.
Definition
Okan is a tropical hardwood species that naturally falls into EN 350 durability class 1. This means the wood, without impregnation or any other treatment, is highly resistant to fungi, insects and moisture for a very long time. The structure is fine-sawn and dense, which provides high mechanical strength. In European standardisation one speaks of EN 350 class 1 (very durable, more than 25 years) and use class EN 335 GK4 (direct and permanent ground contact). Okan is often mentioned together with other tropical hardwoods such as azobe, cumaru and tali. The difference lies mainly in the application: where azobe is typically used in water, Okan is mainly used for structures in the ground — fence posts, pergolas, boundary enclosures and load-bearing beams. See also our comparison Okan vs Tali for decking.
Properties and durability class
Okan combines properties that are rarely found together in one wood species:
- Durability class 1 (EN 350) — very durable, more than 25 years, without treatment.
- Permanent ground contact (EN 335 GK4) — may be placed directly in the ground.
- Fine-sawn and dense — smooth surface, workable with sharp tools.
- Extremely strong — high bending and compressive strength, suitable for load-bearing structures.
- Rot- and insect-resistant — no impregnation needed.
- TLV-certified — sourced from responsibly managed forest.
Untreated exterior wood weathers naturally under the influence of UV and moisture — cosmetic, not structural.
Applications: posts, beams and planks
Okan is supplied in three main formats:
- Posts — from 50x50 mm, for fencing, pergolas, boundary enclosures and structures directly in the ground.
- Beams — 50x100 to 50x200 mm, for load-bearing structures such as canopies and terrace constructions.
- Planks — for cladding and fencing, where a smooth, fine-sawn surface is desired.
Lengths run up to 5 metres. Because Okan can handle permanent ground contact, you do not need concrete pads or adjustable post feet — the post goes directly into the ground. That saves material and weak connections. For projects where the wood does not stand in the ground, Douglas is often a more economical alternative — see hardwood vs Douglas.
Pros and cons
Advantages
- Very long natural service life (class 1, >25 years) without treatment.
- Suitable for permanent ground contact — no concrete pads needed.
- Extremely strong and fine-sawn.
- Naturally resistant to rot and insects.
- TLV-certified.
Disadvantages
- Denser and heavier than softwood; requires sharp tools.
- Price is higher than impregnated pine or Douglas.
- Untreated, the wood weathers naturally.
Maintenance
Okan requires little structural maintenance — that is exactly what the wood is for. Untreated exterior wood weathers under the influence of UV and moisture into an even grey patina, without affecting the structural properties. For those who want to preserve the original colour, periodic oiling is an option. Otherwise the same rule applies to all exterior wood: clean annually with water and a soft brush to keep the surface clean and remove algae and moss. For posts in the ground, check the connections and the wood-to-ground transition annually for cracks or loose fixings.
Okan is the logical choice when you need a strong, durable wood species for structures that stand directly in the ground. View our hardwood range for Okan posts, beams and planks — in stock from Meppel.
Frequently asked questions
Is Okan suitable for permanent ground contact?
Yes. Okan falls into EN 350 durability class 1 and is approved for use class EN 335 GK4 — direct and permanent ground contact. The post can go directly into the ground without a concrete pad or impregnation.
What is the difference between Okan and azobe?
Both are tropical hardwoods in class 1, but the application differs. Okan is mainly used for structures in the ground (posts, beams, planks). Azobe is heavier and is typically used in water — sheet piling, piling walls and quay walls.
How long does Okan last?
Okan belongs to durability class 1, which stands for very durable (more than 25 years) according to EN 350. Properly installed Okan lasts for decades in permanent ground contact without treatment.
Does Okan need to be treated?
No. Okan is naturally rot- and insect-resistant and needs no impregnation or preservation. Untreated, the wood weathers naturally — cosmetic, not structural. Periodic oiling is an option to preserve colour.