As extremely dense, hard lumber species, popular tropical decking choices such as Cumaru and Ipe require a little more TLC when it comes to installation. In a sense, the characteristics that make these premium decking species so incredibly durable are the same characteristics that make them a tad more challenging to install. But with the proper tools and preparation, you can install a Cumaru or Ipe deck without losing your mind — or ruining your tools!
Realize Why It’s Rough
Like other decking lumber species, Ipe and Cumaru are typically quartersawn; this method is used in order to showcase the consistent vertical grain and maximize stability. At the same time, though, quartersawn lumber ends up exposing medullary rays, internal structures of the tree once used to move nutrients from the outer layers to the inner layers of the tree. These dense structures don’t plane easily, so they create a rough surface on the face of decking boards. While all lumber species include medullary rays, these raised structures are much more apparent in extremely hard tropical species such as Ipe. Once you realize that these lighter, raised areas aren’t defects but simply results of using such a hard lumber, you can touch them up with a little sanding and eliminate any extremely rough areas.
Take Time To Optimize Stability
Cumaru and Ipe are highly stable decking species; at the same time, though, they’re still decking species. What we mean is that like other decking products, these tropical hardwoods have much higher levels of moisture than their counterparts, which have been kiln dried for interior use. Typically air dried to moisture levels ranging from 14-18%, tropical decking is prepared to avoid large swings in moisture levels, lessening the chances of warping, cupping, or twisting. However, in order to maximize the stability of decking lumber, you need to give it time to acclimate to the climate of your job site. To do so, store it someplace where it’s not subjected to direct sunlight, stacked to accommodate proper air flow around each board. Typically, we recommend a 2-3 week acclimatization period, during which a 6” decking board might expand or contract up to ¼” — definitely something you want happening prior to screwing that board into the rigid sub-structure.
Plan To Allow for (& Reduce) Future Movement
Like any deck, you’ll need to allow for continued movement due to seasonal moisture level fluctuations by designing the deck with proper ventilation in view. Especially if you’re building a ground-level deck, you need to make sure to allow for proper air flow beneath the boards. And be sure to apply end sealant each time you cut the length of the boards; otherwise, the ends will swell and contract each time moisture levels shift; while we cannot completely avoid this movement, we can slow the process, reducing the occurrence of splitting and checking.