A.Wood finishes expert Bill Feist responds: The National Park Service often specifies vertical-grained Douglas fir for its decks and porches. This wood has a good combination of hardness, moderate rot resistance, dimensional stability (resistance to warping), and cost. This may be a special order item at your lumberyard.
A true mahogany would be the optimum choice for a deck because of its marked durability, its rot resistance, its hardness and wear properties, and its very good dimensional stability. The only major drawbacks are its high cost and limited availability.
to continue reading