Contractor's Guide to Specifying Cumaru

The Smart Premium Alternative to Ipe

Cumaru (Dipteryx odorata), commonly known as Brazilian Teak, delivers mechanical performance nearly identical to Ipe at a more accessible price point. With a distinct, interlocking grain and exceptional durability, it is a frequent spec for both commercial and residential projects.

Physical & Mechanical Properties

Cumaru boasts immense density and hardness, making it highly resistant to rot, decay, and termite attack.

Botanical NameDipteryx odorata
Janka Hardness3,330 lbf (14,800 N)
Specific Gravity0.86 (Basic), 1.09 (12% MC)
Modulus of Rupture22,400 psi (154.5 MPa)
Modulus of Elasticity3,050,000 psi (21.03 GPa)
Crushing Strength13,850 lbf/in²
ShrinkageRadial: 5.0%, Tangential: 7.6%, Volumetric: 12.0%
Fire RatingClass A (ASTM E84) dependent on testing

Architectural Implications

Cumaru's extreme stiffness means minimal deflection under load. Because of its high shrinkage ratio and tendency to move, kiln-dried (KD) Cumaru is strongly recommended for interior or covered applications, while air-dried (AD) is preferred for exterior decking to minimize shrinkage in the field.

Grading & Appearance Expectations

We supply Premium Grade Cumaru, graded for structural integrity and aesthetic consistency.

Color Variation

Ranges from a medium golden-brown to a darker purplish-brown, sometimes with reddish hues. Yellow Cumaru (Standard) and Red Cumaru are sometimes separated, but natural variation is standard. Weathers to a silver-gray if untreated.

Grain Pattern

Strongly interlocked grain with a medium texture and a waxy feel. The interlocked grain gives it excellent slip resistance but requires sharp tools for planing.

Weathering

Excellent weathering characteristics. Can be prone to minor surface checking (hairline cracks) in arid environments if not properly acclimated or oiled.

Installation Specifications

Acclimation & Storage

Critical step: Requires 7–14 days of on-site acclimation. Must be stickered and kept out of direct sunlight and rain. Cumaru has a higher tendency to cup or warp during rapid moisture changes compared to Ipe.

Cutting & Machining

Difficult to work due to density and interlocked grain. Carbide-tipped tools are mandatory. Interlocked grain can cause tearout during routing or planing.

Fastening Systems

Pre-drilling is required. Use 316 stainless steel screws. Hidden clip systems are widely used, but face-screwing provides the most secure hold against cupping in wider boards (e.g., 1x6).

End Sealing

All cross-cuts must be sealed immediately with an aqueous wax emulsion to prevent checking.

Ideal Applications

✓Commercial and residential decking
✓Rainscreen siding
✓Heavy construction and timbers
✓Outdoor cabinetry and furniture

Limitations & Warnings

⚠Higher tendency to warp or cup than Ipe if improperly acclimated or fastened.
⚠Dust can be an irritant; has a distinct vanilla/cinnamon odor when cut.
⚠Requires premium carbide tooling.