Yellow Balau / Bangkirai — Shorea laevis
A dense, premium decking hardwood from Indonesian and Malaysian rainforests — sold as Bangkirai from Indonesia and Yellow Balau from Malaysia. Same species (Shorea laevis), same wood. Class 2 above-ground durability, naturally termite-resistant, with mechanical performance that rivals Ipe and Cumaru. The benchmark species for premium tropical hardwood decking and exterior structural work.
Yellow Balau / Bangkirai products
Pool-compliant screens, batten screens, louvered panels and premium decking — Bangkirai / Yellow Balau is one of the world's most specified tropical decking hardwoods.
Technical ReferenceSummary
Yellow Balau (Shorea laevis) — known throughout Indonesia as Bangkirai and in the Philippines as Yakal — is one of the world's premier tropical hardwoods for outdoor decking and heavy construction. It belongs to the Shorea subgenus Eushorea, a group of high-density Dipterocarpaceae species from Indonesia, Malaysia and the Philippines. The Indonesian name (Bangkirai) and Malaysian name (Yellow Balau) refer to the same species — just different countries of origin.
Heartwood is classified Durability Class 2 (Durable) per NF EN 350 (2016), equivalent to AS 5604 Class 2 above-ground use. Density 930 kg/m³ — exceptionally high. Janka hardness 8.0 kN (1,798 lbf) seasoned. Modulus of rupture 144 MPa, MOE 20 GPa. Heartwood is naturally durable to termites (EN 350 Class D). The species is not formally classified under AS 1720 (strength/joint group) but is rated EN 1912 strength class D50 by visual grading. Shorea laevis is one of the few tropical hardwoods rated for EN Use Class 5 (permanent salt-water immersion) due to its high specific gravity and silica content.
Class 2 of 4
Character & Appearance
Heartwood is yellow-brown to reddish-brown, more or less dark. Weathers to a silvery-grey patina if left untreated, which is often the desired aesthetic for landscape and decking applications. Sapwood is much paler — light brown — but is not clearly demarcated from the heartwood in this species. White resin canals are characteristic of the wood.
Grain is straight or interlocked, with slight interlocking typical of the Shorea family — producing a stripe figure on quarter-sawn surfaces. Texture is medium with a smooth finish. The wood is difficult to work due to high density and silica content — pre-drilling for fasteners is essential, and Stellite-tipped or tungsten carbide tooling is required for extended cutter life. Workability is comparable to Ipe and Cumaru.
Species & General Properties
Mechanical & Physical Properties
| Property | Unseasoned | Seasoned |
|---|---|---|
| Density (12% MC) | — | 930 kg/m³ |
| Specific gravity | — | 0.91 |
| Janka hardness | — | 8.0 kN (1,798 lbf) |
| Modulus of rupture (bending) | — | 144 MPa |
| Modulus of elasticity | — | 20.0 GPa |
| Crushing strength | — | 85 MPa |
| Monnin hardness | — | 7.3 |
| Strength Group (AS 1720) | Not classified | Not classified |
| Shrinkage (Total) | Value |
|---|---|
| Tangential shrinkage (green to oven-dry) | 9.3 % |
| Radial shrinkage (green to oven-dry) | 4.2 % |
| T/R ratio | 2.3 |
| Volumetric shrinkage coefficient | 0.68 % per % |
Recommended Applications
Yellow Balau / Bangkirai's combination of Class 2 above-ground durability, very high density and natural termite resistance makes it one of the most specified SE Asian hardwoods worldwide for decking, marine work and external structural applications.
Specification Notes
- Natural durability ratings apply to heartwood. Sapwood is not clearly demarcated from heartwood in this species; specify heartwood material where possible.
- Recommended spec wording: "Yellow Balau / Bangkirai (Shorea laevis) heartwood — EN 350 Durability Class 2, equivalent to AS 5604 Class 2 above-ground durability. Density 930 kg/m³, Janka 8.0 kN seasoned. EN 1912 strength class D50."
- Strength group (AS 1720): Yellow Balau is not formally classified under AS 1720. For structural applications, specify by species name and EN 14081 grading (strength class D50).
- Termite resistance: heartwood is naturally durable to termites (EN 350 Class D).
- Working characteristics: Difficult to cut, plane and sand — similar to Ipe and Cumaru. Pre-drilling essential for fasteners. Carbide-tipped or Stellite-tipped tools recommended. Tends to split with nailing — pre-bore.
- Fastener compatibility: Use stainless steel (316 for coastal, 304 inland) or hot-dipped galvanised fasteners due to high density and oil content.
- Sourcing: Kosny sources Yellow Balau / Bangkirai from legal and traceable supply chains in Indonesia and Malaysia.
References
Speccing Yellow Balau / Bangkirai for a project?Yellow Balau / Bangkirai for a project?
Decking, screens, louvered panels in stock — structural and bulk sections supplied to order. Class 2 above-ground SE Asian hardwood with legal chain of custody from Indonesian and Malaysian mills.