Balau
Shorea spp.
Also known as selangan batu, yellow balau · Botanical Shorea spp.
Revision history
- — Data re-verified in site-wide audit (formulas, sources, durability classes)
- — Working properties and comparable-species data cross-checked against listed sources
About Balau
Balau (Shorea spp.) is a hard, wear-resistant timber that is heavy going on tools, with a Janka hardness of 1,700 lbf (7,562 N) and a density of about 0.78 g/cm³. It grows in Southeast Asia and the Pacific.
At 3.5% radial and 6.5% tangential the T/R ratio is 1.86 — typical, and manageable in exterior joinery and cladding provided the gaps are designed rather than assumed. Its fibre saturation point is near 26%. Below it the wood shrinks steadily — 6.5% tangential, 3.5% radial. Ordinary territory: design the gaps rather than hoping the finish will hold it.5% tangential against 3.5% radial, quartersawn stock will behave noticeably better than flatsawn.
At 780 kg/m³ a cubic metre of Balau weighs about 780 kg air-dry — that figure, the 6.5% tangential and 3.5% radial movement and the 1,700 lbf hardness are the three inputs the calculators below actually consume. Select Balau in any of them to get species-specific results for weight, moisture, shrinkage and hardness.
Working properties
How Balau behaves at the bench and on the machine, drawn from WoodSolutions Australia, Malaysian Timber Council data and international hardwood references.
Durability & use classification
Balau heartwood is rated durable (EN 350 Class 2), with graveyard testing of one species (S. maxwelliana) giving a service life near 15.8 years in ground — consistent with the 15–25 year figure above. An important honest caveat: “balau” is a trade name covering many Shorea species, and durability genuinely varies between them — yellow balau is the durable benchmark, while red balau is materially less so. The sapwood is perishable and prone to pinhole borer, and the heartwood is extremely difficult to treat.
Typical applications & suitability
Indoor Outdoor — Primarily an exterior and heavy-structural timber — one of the standard South-East Asian decking woods — though it serves indoors for high-traffic floors too.
Documented end-uses: decking and heavy-traffic flooring, marine and freshwater construction, wharves, jetties and piers, bridges and cooling towers, railway sleepers, piling, beams, columns and joists, boat building (keels and framework), door and window frames, staircases, heavy-duty furniture and impact tool handles.
Comparable species
Species closest to Balau by density, hardness, stiffness and bending strength, computed directly from the Vriksai species dataset rather than hand-picked.
Trade alternatives. Its closest relatives and substitutes are Bangkirai and Merbau from the same region, or Garapa from South America. Note the naming confusion: balau, selangan batu and bangkirai overlap in trade, and Sal shares the same Shorea genus.
Alternatives to Balau
Balau measures 1,700 lbf Janka at 0.78 g/cm³, EN 350 durability Class 2, movement rated Good. Anything replacing Balau outdoors has to hold Class 2 durability and carry the load — so nothing below that class appears here, however well it matches on hardness. Read the numbers against the Janka scale and EN 350 durability classes.
For decking, marine work and structural exposure where the surface takes impact as well as weather. Expect slower machining, faster tool wear and more weight to handle on site.
Lighter sections, easier fixing and lower freight per m³ — while holding the exterior durability class. Useful where the spec is over-engineered for the actual load.
Exterior sections move most, and a dense timber that moves takes fixings and joints with it. These hold their dimension better in the same durability class. Size the gaps with the shrinkage predictor and EMC calculator.
If Balau is unavailable and the specification cannot change, these are the nearest substitutes across hardness, density, movement, stiffness, bending strength and durability class together — not on any single property. Lower distance means a closer match.
Computed from measured properties only — hardness, density, movement, stiffness, bending strength and EN 350 class. Price, availability and appearance are never inputs. Figures are representative values, not consignment absolutes: two species within a few percent are equivalent until verified on the material. Full method and the rules the engine cannot break.
Substituting outdoors is a match on durability class and movement first. Colour and grain can be matched later; a wrong durability class shows up as a callback in three monsoons. Where two candidates are close, compare them directly before specifying.
Compare Balau side by side
The pairings below are the ones that actually come up in exterior and structural tendering. Every pairing shows the measured figures side by side; full matrix in the comparison index.
Calculators relevant to Balau
Sized for exterior and load-bearing work in Balau — spans, fixings, weathering gaps and freight weight. Full set in the tool index.
Understand the figures
Janka hardness scale — how the lbf figure is measured · Wood density reference — oven-dry vs air-dry basis · Moisture content — EMC, FSP and service conditions · Strength properties — MOR, MOE and what they govern.
Further reading. Wood moisture content explained · How to calculate board feet.
Common questions about Balau
unverified no published source for this figure · FPL USDA FPL Wood Handbook GTR-190 · WD The Wood Database (Eric Meier) · calc derived from the figures above