Avoiding Potential Problems with Tropical Hardwood Decking.
While tropical hardwood decking is a great upscale option, it does have some drawbacks. Anticipating and allowing for them can help ensure a positive experience. The first major potential problem to look out for is warping. Stability is a major concern for exterior lumber, in general, and tropical hardwood decking, in particular. Even the best decking species, like Cumaru and Ipe, can be susceptible to warping.
When lumber is used outdoors, it has a much higher moisture content than lumber used indoors. However, when the lumber is air dried to a moisture level between 14 & 18%, it resists major swings in moisture content, thus preventing the kind of rapid expansion that leads to warping. If, instead, the wood is kiln dried to less than 8% moisture content, the thirsty boards would soak up a lot of moisture with the first rain or during times of high humidity.
In order to benefit most from the air drying, decking lumber should be stored in the area of the job site for an acclimatization period of at least 2 or 3 weeks, with good air flow and out of direct sunlight. You can expect the wood to expand or contract up to 1/8” on 4” wide boards and 1/4” on 6” boards, as it comes into equilibrium with the local climate. By allowing the wood to move before it’s attached to a rigid sub-structure, you can prevent problematic warping.
In addition to air drying and acclimatization, using quartersawn lumber can help maximize stability of tropical hardwood decking. In addition to promoting stability, quartersawn lumber showcases the consistent vertical grainstriping on the face by exposing the medullary rays. These dense internal structures are used by the tree to transport nutrients from the outer layers to the inner layers of the tree. The downside to exposing these structures is that they often resist planing, so the boards are not as smooth. While this issue comes up with all lumber species, it’s especially noticeable in tropical hardwoods, making sanding necessary to get a smooth finish.
As you design your new tropical hardwood deck, you can further encourage optimal stability by making sure to offer proper ventilation on the ground side, in order to promote even air flow and expansion during seasonal shifts in climate and moisture levels. Whenever fresh grain is exposed, moisture content can change quickly at the ends, so as the tropical hardwood decking boards are cut to length, proper end sealant should be used in order to slow moisture change. A wax-based coating such as AnchorSeal can alleviate unattractive issues such as splits or checks.
As long as these precautions are taken, tropical hardwood decking is indeed quite stable and will provide you with a quality deck that requires little maintenance and stands the test of time.