- 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.