Iron Woods Cumaru Decking

Cumaru (Dipteryx odorata) a.k.a Brazilian Teak – This Brazilian species is similar to Ipe in many respects and is most often used as a lower cost alternative in commercial applications. The grain has a pronounced interlocked appearance.

Similar in appearance to Ipe, it can at times be difficult to differeniate to the less trained eye. Cumaru does however have a more course and interlocking grain which results in lower dimensional stability in both storage and application. Cumaru is currently being used heavily in the commercial boardwalk industry in 2×4 decking as a lower cost alternative to Ipe. Cumaru has been considered an equal to Ipe in Atlantic City for over a decade.

Strength & Durability

Cumaru is a golden to reddish brown species of tropical hardwood with similar technical properties to Ipe with exception of its resistance to termites.

How does Iron Woods® Cumaru compare to other lumber and decking products?

Cumaru CCA-Treated Pine Composite Decking
Type Hardwood Softwood Plastic Wood
Maintenance Low High Low
Decay Resistance High Varies Varies
Termite Resistance High Varies Varies
Strength High Medium Low
Movement in Service Medium-Low High High
Fire Rating Class High Varies Low
Weight per cu. ft. 67lbs. 35lbs. 60 to 64lbs.
Bending Strength 22,400 9,900 – 14,500 1,423 – 4,500
E-modulus 3,010,000 1,170,000 – 1,510,000 175,000 to 480,000
Shear Strength 2,395 1,370 561 – 1,010
Hardness 3,340 690 940 – 1,390

See how it compares to the rest of our line

Suitable Applications

Cumaru is available in two varieties; Yellow Cumaru and Red Cumaru. Cumaru is best used in applications such as commercial decking, boardwalks, bridges, benches and exterior construction.

Residential Decking – It is highly recommended that residential decking dimensions up to 5/4x6 be kiln dried to increase stability and reduce grain lift. Cumaru is difficult to dry in thicknesses greater than 1 inch. Heavier and wider dimensions are not recommended for residential applications.

Commercial Decking and Timbers – Cumaru can be used air dried for commercial decking applications. We do not recommend exceeding 2x6 for light commercial decking, as stability decreases as width increases. Dimensions up to 3x12, 4x12 and 6x12 have been used successfully and with good stability in heavy commercial decking and timber applications.

Availability

Decking – 1x6, 5/4x6, 2x4, 2x6
Timbers – up to 12x12 by special order only.

All other dimensions up to 12x12 clear of heart center are special order only.

Residential Deck Installation & Maintenance

Cumaru is a low-maintenance decking. It naturally weathers into light silvery gray tones – there’s no need to apply annual sealers. To enjoy its warm golden-brown hues, a simple application of an outdoor finish can be periodically be applied to maintain its beauty. Consult our installation guide, available at your dealer, for more outdoor finishes and hints on working with Cumaru.

Storage & Handling

Iron Woods® Cumaru decking is supplied as kiln dried lumber and is for outdoor use only. Store the wood out of direct sunlight and be sure to keep it dry and off the ground. Allow the wood to acclimate and stabilize to the installation area’s humidity before installing.

We recommend carbide-tipped saw blades and high-quality drills for smooth cuts.

Spans/Spacing

These spans are are designed for Cumaru to allow for minimal deflection of the deck surface. For maximum spans and engineering data, you can contact us.

Load Size
Board Size 100psf
1x4 16″
1x6 16″
5/4x6 24″

Allow a 3/16″ gap between 6″ wide deck boards and a 1/8″ gap between 4″ wide deck boards for drainage, airflow and expansion. Kiln dried decking may expand 1/8″ on 6″ wide boards during times of high moisture. Expect some shrinkage in width in hot or dry areas.

Deck Ventilation

Adequate ventilation of the deck is essential for long-term stability and to minimize cupping. Proper air ventilation allows air to flow in from outside the deck area, under the joists and up through the gaps between the deck boards.

Fasteners

For screws, we recommend a high-quality, stainless steel trim head screw. Though coated or galvanized screws may also be used, they generally cause black staining and have a shorter service life. To install Iron Woods® Cumaru, you must pre-drill a pilot hole and countersink to avoid splitting and then fasten with the stainless steel screws, which are available at Iron Woods® dealers.

Finishing

Seal Iron Woods® Cumaru immediately after installation to reduce the potential for surface checking. If installing over a prolonged period or during hot weather sealing after each phase is recommended. Be sure to seal all ends immediately after cutting with Anchorseal clear wax end sealer (available from your Iron Woods® dealer) in order to reduce end checking.

To maintain its color, use a transparent, penetrating oil-based sealer with UV inhibitors in a trans-oxide pigmented tint and reapply annually or as needed.

If you prefer a natural, silvery-gray appearance, use a clear oil-based sealer for the first coat and then simply let the wood weather to its natural gray color. If you want to return silver-gray wood to the original color, use a “wood brightener.” Careful power washing and/or sanding can help to remove the grayed wood.

Download

Download a printer-friendly PDF of this Installation & Maintenance guide. Click the link to open/download the PDF in most browsers. You can also right-click and choose to Save Link As.

More Information

For further details on the installation of Iron Woods® Cumaru, you can contact usat any time.