What Screws to Install for 5/4 X 5 Cedar Decking?

Deck Screw Length

• The basic rule of thumb for appropriate-length screws is to select screws that are three times as long as the thickness of the decking board. Once cured, a 5/4-inch-thick decking board is approximately 1 inch thick. Using 3-inch screws, one-third of the screw is in the decking board and the remaining two-thirds of the length of the screw is in the joist.

Deck Screw Composition

• Commonly used decking screws are typically either coated hardened steel or stainless steel. Stainless steel screws are recommended for use on cedar and redwood decking. Coated hardened-steel screws are specially manufactured for use with pressure-treated fir and pine. The coated deck screws can, over time, discolor the cedar. Acidic sap in cedar and redwood may corrode the finish on coated decking screws. Stainless steel screws are also recommended in humid climates or in areas subject to salt-water spray.

Special Features

• Square-drive deck screws are less prone to stripping than Philips-head screws and allow greater torque during installation. Auger-tipped decking screws are self-starting and eliminate the need for pilot holes.

Through Fastening

• A through-fastened deck offers the highest level of board-to-joist connection strength. Using this method, decking boards are positioned perpendicular to the joists with the concave surface of the tree rings facing downward to prevent cupping. Two decking screws attach the 5-inch wide plank to each joist, using a drill and driving bit or a screwdriver. To conceal the screw head, some builders countersink the head of the screw, then cover it with a dowel plug.

Concealed Side-Fastening

• For a clean look without visible fasteners, many manufacturers offer decking-board fastening kits with concealed screws. One type has a steel plate that attaches to the upper side of the joist. Screws, included in the kit, are installed at an angle from beneath the deck. Another common system uses clips that toenail the edge of the decking board to the joist.