- Q. I’m building a wharf on a bay of the Gulf of Mexico. It is to be on 8-inch-diameter pilings with 2-by joists and cross-members. Can I use plywood for the decking? What are your recommendations?
A.Mike Shannahan, a master carpenter in La Porte, Texas, responds: Plywood would not be my choice for the decking; even treated plywood can have problems with delamination when used in the open on a project like the one you describe. Plywood would also be at a disadvantage in the harsh wind and high water conditions that occur during tropical storms and hurricanes: The "lift" on 4x8 sheets could wreak havoc on framing connections and bearing members when wind and wave action team up on your dock.
I would use 2x6 or 2x8 decking of pressure-treated Southern Pine (.60-retention) nailed in place with 20-penny hot-dipped-galvanized spikes. Space the deck boards 3/4 inch to 1 inch apart to allow plenty of room for movement and for water to flow through during storm tides. All heavy members below the deck — cross ties, stringers, joists, and so forth — should be bored and through-bolted with hot-dipped-galvanized or stainless-steel fasteners.
Some excellent publications on the marine use of Southern Pine are available from the Southern Forest Products Association (P.O. Box 641700, Kenner, LA 70064; 504/443-4464). Good luck.