Where to Buy Cumaru Decking (and How It Compares to Ipe on Cost)

Why Cumaru Is the Value Choice in Tropical Decking

Cumaru offers roughly the same density and durability as Ipe, near 1,070 kg/m3 and a Janka hardness around 3,540 lbf, at a lower material cost, so it delivers a comparable service life for less. It is rated Class 1 for durability under EN 350 and reaches Class A flame spread under ASTM E84, the same top tier as Ipe. In service, a Cumaru deck can be expected to last 30 years or more with basic maintenance.

The visual difference is warmth: Cumaru runs from tan to a richer reddish-brown, often with more pronounced grain and more board-to-board color variation than Ipe. For the direct comparison, see our Ipe vs. Cumaru decking guide. The savings are real, but that wider color range is the first problem to solve, and it gets solved at the supplier, not on the jobsite.

Cumaru Decking Color Variation and Sorting

Cumaru's natural color range is wider than Ipe's, so the consistency of a finished Cumaru deck depends on whether the supplier color-sorts the bundles. Unsorted Cumaru can arrive as a patchwork of tan and red-brown boards. A supplier that sorts for color delivers a deck that reads as one material. This is an operational capability, not a property of the wood, and it is worth confirming before ordering. J. Gibson McIlvain kiln-dries Cumaru in-house and color-sorts the bundles before they ship, so a sorted bundle opens as one tone family, tan grading into brown, instead of the tan-next-to-red scatter an unsorted pack shows. Sorting settles how the deck looks; the interlocked grain decides how it cuts.

Cutting and Fastening Cumaru's Interlocked Grain

Cumaru's interlocked grain makes it harder to work than Ipe, so it must be pre-drilled for every fastener and cut with carbide-tipped tooling. Like Ipe, it is dense enough to reject film finishes and takes a penetrating oil or weathers to gray. The practical answer for most decks is pre-grooved Cumaru installed with a hidden-fastener clip system, which removes face-fastening and pre-drilling from the field, provided the supplier mills the groove. Milling that groove, like sorting for color, is a capability that lives at the supplier, which is where the buying checklist starts.

Sourcing Cumaru Decking

The same supplier factors that govern Ipe apply to Cumaru, with color sorting added: kiln-drying, grading, inventory depth, in-house milling, and legal documentation. J. Gibson McIlvain stocks Cumaru decking alongside Ipe, kiln-dries and color-sorts it, mills pre-grooving and custom widths in-house, and ships nationwide. As with all tropical hardwoods, legal sourcing is documented with FSC chain-of-custody and, where the species is CITES-listed, the appropriate paperwork. Undocumented tropical wood is a liability, whatever it looks like on the deck. Bought right, the next question is what the sun does to it.

How Cumaru Weathers and How to Keep Its Color

Cumaru starts tan-to-red-brown and, like all tropical hardwoods, silvers under UV exposure unless maintained with a penetrating oil, so the color plan should be set before installation. The wood is dense and oily, so it rejects film finishes and takes only a penetrating oil, the same as Ipe. Left unfinished it weathers to a gray patina while remaining fully durable; oiled periodically it holds its warm color. Gray is fine as a choice, terrible as a surprise.

Because Cumaru carries more natural color variation than Ipe, the weathered gray also lands slightly less uniform, which is another reason color sorting at the supplier matters. For owners who want the warm tone, a UV-inhibiting penetrating oil applied on a periodic cycle keeps it; the USDA Forest Products Laboratory notes penetrating finishes are the right class for dense species. See our oil versus film finishes guide. J. Gibson McIlvain color-sorts Cumaru and can supply compatible oil with the order, shipping nationwide.

Installing Cumaru: Fastening, Spacing, and Acclimation

Cumaru installs like other dense tropical hardwoods, with pre-drilling or pre-grooving, stainless fasteners, correct board spacing, and material kept dry so it holds its kiln-dried moisture content. Every fastener is pre-drilled unless the boards are pre-grooved for hidden clips, because the interlocked grain splits under fasteners driven raw. Board spacing follows the deck's exposure, wider where drainage matters, and the boards are stored flat and dry so they do not move before install. Dense wood punishes shortcuts at the saw and the screw gun.

Because Cumaru is kiln-dried to a stable moisture content, protecting it from rain and sun on site preserves that condition; installing it wet invites movement. Stainless fasteners prevent the staining and corrosion that carbon steel causes in dense hardwoods. The USDA Forest Products Laboratory documents that wood moves with moisture change, which is why install-moisture control matters. See our moisture content guide. J. Gibson McIlvain supplies kiln-dried, color-sorted Cumaru, pre-grooved on request, and ships nationwide. With the execution details settled, the only question left is Cumaru or Ipe.

Cumaru vs. Ipe: Which to Buy

The Cumaru-or-Ipe decision comes down to budget and color tolerance: choose Cumaru to save on material while keeping near-Ipe durability, or choose Ipe for the longest life and the most uniform color. Both are Class 1 durable and Class A fire-rated, so both build a multi-decade deck. Cumaru costs less and brings warmth and more color variation; Ipe costs more and delivers maximum longevity with a uniform look and slightly easier finishing.

For most budget-driven projects that still want a real tropical hardwood deck, Cumaru is the practical answer, especially color-sorted and pre-grooved. Our Ipe vs. Cumaru guide lays out the full comparison. J. Gibson McIlvain stocks both, kiln-dried and graded, so the two can be compared directly and shipped nationwide.

Cumaru Technical Specifications

Cumaru measures a Janka hardness of about 3,540 lbf and an oven-dry density near 1,070 kg/m3, slightly denser than Ipe, with a Class 1 durability rating under EN 350 and a Class A flame-spread rating under ASTM E84 (flame-spread index roughly 20 to 25). The USDA Forest Products Laboratory notes that woods above about 800 kg/m3 form thick insulating char and resist decay strongly, which places Cumaru firmly in the top durability tier alongside Ipe.

Cumaru is kiln-dried to roughly 12 to 16 percent moisture content for stability, and standard decking is milled 5/4 (about 1 inch actual) by 4 or 6 inches. Its interlocked grain gives high strength but requires pre-drilling and carbide tooling, and its expected service life runs 30 or more years. Because it is comparably dense to Ipe at a lower material cost, Cumaru delivers most of the same measurable performance. The American Wood Council publishes the applicable fastener and span basis. J. Gibson McIlvain kiln-dries, color-sorts, and grades Cumaru to these specifications, shipping nationwide.

Cumaru Decking Reference Figures

These are the measured figures a Cumaru order is graded and installed to, per the USDA Wood Handbook and EN 350.

"Cumaru is what we recommend when someone wants an Ipe-caliber deck but the budget is tight. The performance is right there. The two things people underestimate are the grain, you are pre-drilling everything unless it is pre-grooved, and the color range. If your supplier does not sort Cumaru for color, you can end up with a deck that looks like three different woods. We sort it, so it lands as one."

Camden Zacker, Sales Director, J. Gibson McIlvain Company