What is bankirai wood?
The Wood Guide · The wood register
Tropical hardwood · referenceBangkirai
Also called bangkirai or yellow balau. Heavy, golden brown and naturally so durable that it lasts more than 25 years — even in the ground.
- Shorea laevis · Shorea glauca
- 850–1,100 kg/m³ — very heavy
- Durability class 1
Bankirai in brief
A tropical hardwood from the rainforests of South-East Asia, from trees of the genus Shorea. For decades the classic choice for decking — and not without reason.
What makes bankirai special is the combination of weight and durability. At 850 to 1,100 kg per cubic metre, it is one of the heaviest species you will find in a garden — heavier than oak, even heavier than teak. That density translates directly into resistance to weather, insects and wear.
It reaches durability class 1: more than 25 years, even in ground contact. That puts it in the same class as teak.
- Botanical
- Shorea laevis (Indonesia), Shorea glauca (Malaysia)
- Heartwood
- golden brown to dark brown, sometimes reddish
- Sapwood
- paler and clearly distinguishable
- Density
- 850–1,100 kg/m³
- Outdoors
- class 1 — 25+ years, even in the ground
- Maintenance
- none; weathers to silver grey
To be fair: fresh bankirai leaches tannins that leave brown streaks on light paving, and it can splinter. Both are temporary or fixable, but you need to know about them.
Three spellings, one wood
Bankirai, bangkirai and yellow balau are the same tropical hardwood, from trees of the genus Shorea in the rainforests of South-East Asia. From Indonesia the species is Shorea laevis, from Malaysia Shorea glauca.
Click a chapter or use the arrows · years and seasons speeded up, streaks and splinters enlarged.
From the rainforests of South-East Asia
'Bankirai' is a trade name that covers two closely related species, depending on the country of origin.
| Country of origin | Botanical name |
|---|---|
| Indonesia | Shorea laevis |
| Malaysia | Shorea glauca |
As a tropical hardwood from primary rainforest, forestry practice is a real concern here. Ask your supplier where the wood comes from and how the forest is managed. If you are looking for a European alternative with comparable performance, look at robinia — class 1–2, with a rotation of 20 to 30 years, grown close to home.
How to recognise it
Colour
Golden brown to dark brown heartwood, sometimes with a reddish tint. The sapwood is clearly paler and easy to tell apart.
Texture
Fine to moderately coarse, with a strikingly even structure.
Grain
Straight to interlocked — the interlocked grain makes planing a little harder, but also gives the wood its toughness.
Weight
Lift a board and you know at once: this is one of the heaviest species on the market.
Technical properties
| Property | Value | What that means |
|---|---|---|
| Density | 850–1,100 kg/m³ | Very heavy — heavier than oak and teak |
| Durability class | Class 1 | More than 25 years, even in ground contact |
| Radial shrinkage | ±0.5% | Limited |
| Resistance | High against weather and insects | Needs no treatment to survive |
| Ageing | Weathers to silver grey | A surface process; the core stays intact |
That weight has a practical downside: bankirai decking needs a sturdy substructure, and you won’t move loose pieces on your own in a hurry. More on how those classes work is in our hardwood guide.
What bankirai is used for
Decking and boardwalks
The classic use, and probably why you are here. See also wood for your decking.
Jetties and bank revetments
Class 1 means it holds up even in permanently damp conditions.
Garden structures
Posts, fencing and heavy outdoor structures — where the weight is actually an advantage.
Outdoor furniture
Possible, but heavy. For furniture you move around often, something lighter is a better choice.
Two things to know
Bankirai is excellent wood, but it has two quirks that catch people out.
The brown streaks
In the first months, fresh bankirai leaches tannins. That leaves brown streaks on everything below it: light paving, white walls, a freshly poured patio. It usually disappears by itself, but on a light surface you can help it along by rinsing after rain for the first few weeks.
Not as smooth as ipé
Bankirai is hard but less dense than ipé, and the interlocked grain can lift. If you walk barefoot on your decking, choose a smooth board or give it a light sanding along the grain after the first season.
For durability, you don’t need to do anything; the wood then weathers to silver grey. If you want to keep the golden brown, oil it every year with a wood oil in the right colour. Half measures don’t work: decking you oil once and then forget looks blotchy.
Frequently asked questions about bankirai
How long does bankirai last?
Durability class 1: more than 25 years, even in ground contact. That puts it in the same class as teak.
Why are there brown streaks on my paving?
They come from tannins that fresh bankirai leaches in the first months. They usually disappear by themselves; on light paving you can help by rinsing after rain until the tannins have washed out.
Does bankirai splinter?
It can. Bankirai is hard but not as dense as ipé; on decking where people walk barefoot, a smooth board or a light sanding after the first season is well worth it.
Is bankirai the same as bangkirai?
Yes. Bankirai, bangkirai and yellow balau all refer to the same tropical hardwood from trees of the genus Shorea. The spelling varies by supplier.
Do you sell bankirai?
No. Our furniture is made of pressure-treated spruce, Douglas fir, teak and other hardwood. Bankirai is in our register because it is the most asked-about wood for decking — and because those tannin streaks surprise people all over again every spring.
Bankirai in perspective
Bankirai is a reference species in our register — wood we don’t use, but do know well.
Have a question about your project? Just ask — we're happy to help.
Photos via Wikimedia Commons: Shorea laevis — No machine-readable author provided. Kinou~commonswiki assumed (based on copyright claims)., CC BY 2.5 · Shorea — G-Lignum, CC BY 4.0