Cumaru
Dipteryx odorata
Also known as Brazilian teak, tonka · Botanical Dipteryx odorata
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 Cumaru
Cumaru (Dipteryx odorata) is one of the hardest timbers in commercial use, extremely wear-resistant and slow to machine, with a Janka hardness of 3,540 lbf (15,746 N) and a density of about 0.87 g/cm³. It grows in South America.
Radial 5.3% against tangential 7.7% is an unusually even T/R ratio of 1.45 — Cumaru shrinks close to uniformly, which is why it holds a flat panel in exterior joinery and cladding. Its fibre saturation point is near 25%. Below it this timber moves a great deal — 7.7% tangential — but evenly, at a T/R ratio of 1.45. Wide boards need genuine expansion room; they are less likely to cup than to simply change width. — wide boards need real expansion room, not a token gap.
At 870 kg/m³ a cubic metre of Cumaru weighs about 870 kg air-dry — that figure, the 7.7% tangential and 5.3% radial movement and the 3,330 lbf hardness are the three inputs the calculators below actually consume. Select Cumaru in any of them to get species-specific results for weight, moisture, shrinkage and hardness.
Working properties
How Cumaru behaves at the bench and on the machine, drawn from the CIRAD Tropix tropical-wood database and international decking-timber technical data.
Durability & use classification
Cumaru is rated very durable (EN 350 Class 1), resistant to brown- and white-rot fungi, dry-wood borers and termites, and it is commonly reported at Class A flame spread (ASTM E84) — indicative only; see the fire note above, as a certified rating attaches to a specific tested product, not to a species. A cumaru deck can serve 50 years or more with little maintenance. Its heartwood is effectively impermeable to treatment.
Typical applications & suitability
Indoor Outdoor — A true exterior hardwood, marketed as ‘Brazilian Teak’ — ideal for decks, high-traffic and high-exposure work — while its density and figure also make an exceptionally hard-wearing interior floor.
Documented end-uses: decking, siding and pergolas, exterior and interior flooring, outdoor furniture, cabinetry, countertops and trim, plus heavy construction, docks, railway sleepers, bearings, tool handles and turned objects.
Comparable species
Species closest to Cumaru by density, hardness, stiffness and bending strength, computed directly from the Vriksai species dataset rather than hand-picked.
Trade alternatives. Where cumaru's weight or cost is an issue, comparable very-durable hardwoods are Ipe and Massaranduba from South America, or Merbau from South-East Asia. Note cumaru is CITES Appendix II listed, so source it traceably.
Alternatives to Cumaru
Cumaru measures 3,330 lbf Janka at 0.87 g/cm³, EN 350 durability Class 1, movement rated Excellent. Anything replacing Cumaru outdoors has to hold Class 1 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 Cumaru 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 Cumaru 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 Cumaru
Sized for exterior and load-bearing work in Cumaru — spans, fixings, weathering gaps and freight weight. Full set in the tool index.
Understand the figures
ThermoWood species guide — Thermo-D/Thermo-S treatment classes · 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.
Further reading. Wood moisture content explained · How to calculate board feet.
Common questions about Cumaru
unverified no published source for this figure · WD The Wood Database (Eric Meier) · calc derived from the figures above · — no published source found