Changes in Cumaru Quality – A Customer Advisory

For decades, Cumaru has been one of the most popular Brazilian Hardwoods in the United States. Its reputation for durability and beauty earned high praise across the entire industry—including from us here at Brazilian Wood Depot.

Unfortunately, something has changed. Over the past 4–5 years, the quality of Cumaru arriving in the U.S. has shifted in ways we cannot ignore. While the exact cause isn’t fully clear, we believe it stems from changes in harvesting locations. What we do know is that today’s Cumaru is simply not performing as it once did.

What We’re Seeing in Cumaru Today

Unstable boards that are far more prone to warping.

Cracking and splintering in ways we never saw in past decades.

Less consistency overall, especially compared to other Brazilian hardwoods.

These issues mean that Cumaru no longer meets the same standards of performance our customers have come to expect from Brazilian Wood Depot.

A Case Scenario

Below are photos of a Cumaru deck purchased from one of our major competitors. When the customer was unable to reach a satisfactory resolution with that distributor, he contacted us and ultimately chose an alternative hardwood species instead.

As you can see, the deck was installed correctly. Airflow beneath the boards was sufficient, and the fasteners and spacing were consistent with professional installation standards. Unfortunately, despite proper installation, the Cumaru boards warped significantly after being put in service.

It’s unclear whether this material was properly kiln-dried at the source in Brazil. However, we’ve observed performance issues, of a variety of types, with Cumaru in recent years, regardless of supplier.

Other Case Scenarios

We’ve also seen some Cumaru boards develop a noticeable “wave” along their length—most commonly in heavy sun exposure and when installed with hidden fasteners. This does not happen in every case, but it occurs often enough to be a concern.

It’s important to note that all hardwood boards will develop some surface “checking.” Checking refers to small surface cracks that do not penetrate through the board and are completely normal. However, in the examples below, the checking is heavier than what we typically see in other hardwood species.

In addition, the crack along the edge of the board suggests the wood was under unusual pressure and stress. The source of this stress may have been airflow-related, though that was never fully determined.

In some (more rare) cases, there have also been reports of splintering with Cumaru. All wood has the potential to create splinters, but our hardwoods are known for being virtually splinter-free when installed correctly. We have documented at least one case with Cumaru where splinters became pervasive—despite proper installation and no fault of the homeowner or installer.

What We’ve Done to Protect Our Customers

At Brazilian Wood Depot, we’ve taken extra steps to ensure that anyone who still chooses Cumaru receives the highest quality material available today. Over the past several years, we have:

Culled through hundreds of Cumaru boards to weed out the worst performers and hand-select only the best material.

Accepted the reality that this increases our overhead on Cumaru, which in turn means the prices we offer are higher than some competitors.

Made sure that our customers receive the very best Cumaru still available—not just whatever comes off the boat.

Moving Forward

Cumaru remains a popular choice in the market, and for that reason we continue to carry it in our product lines. However, we believe it’s important to be transparent about its limitations. Our priority is to educate customers on where Cumaru can—and cannot—perform reliably, while also guiding them toward hardwood alternatives that will better meet long-term expectations.

If you want decking or siding to perform for decades, other hardwood species may provide more dependable results. At minimum, we strongly recommend the following guidelines for anyone choosing Cumaru:

Avoid heavy sunlight exposure – Cumaru is more prone to movement and instability in direct, prolonged sun.

Do not use hidden fastening – especially in heavy sunlight conditions. Use surface-mounted fastening wherever possible.

Ensure maximum airflow – proper ventilation below the deck, along with correct spacing and blocking per BWD standards, is essential.

Our mission has always been to deliver honest guidance, premium materials, and unmatched support. That promise hasn’t changed—and it never will.

Changes in Cumaru Quality – A Customer Advisory

What We’re Seeing in Cumaru Today

A Case Scenario

Other Case Scenarios

What We’ve Done to Protect Our Customers

⚠️ A Word of Caution:

Moving Forward

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