Because decking provides the surface appearance of your deck, you may want to invest a little more for high quality lumber such as cedar or redwood. Even if you choose to use pressure-treated lumber for your decking, measure and install it with care.
Fixing bow and warp
If some decking boards have slight bows (and they will), you can correct them during installation. Fasten the bowed board at each end, then insert a flat pry bar along the bow. For an inward bow, fit the pry bar between the last finished board and the bowed one, and pull back until the bowed board is straight. Fasten before you let go.
For an outward bow, drive the pry bar into the joist next to the bow, pull back on the bar to straighten the board, and nail or screw it in place. This is the first board laid either at the header joist or along the house. Starting at the header allows you to make minor adjustments to spacing next to the house, where it won’t be as noticeable. In either case, measure and cut the starter board to the exact length of the deck and fasten it in place.
The Rest of the deck
Lay out the remaining decking with ends overhanging the joists; you will cut them off later. Before you start to fasten the decking, arrange it so joints are centered on joists and fall in a random pattern. Space untreated lumber Vs inch apart (an 8d nail makes a handy spacer). Butt treated lumber together; it will shrink the first year. Fasten each board with nails or decking screws, drilling pilot holes at butt joints (or on all of the ends) to avoid splitting.
As you approach the ledger (or the header, if you started at the house), lay the boards exactly as you will fasten them and make adjustments in the spacing. (You may have to rip the final boards to fit.) Leave 74-inch space between the last board and the house to allow for expansion.
trim the ends: When all the decking is fastened, snap a chalk line from the starter board to the ledger, and trim the ends of the decking with a circular saw. Tack a 1×4 on the decking to keep the saw on the line. Set the saw to the exact depth of the decking to avoid scoring the face of the end joists.
A diagonal pattern requires some exceptions: Joists must typically be spaced 12 inches on center. To lay your starter board, measure 3 feet from a corner on both the header and end joist. Start at this point and lay decking on either side of the starter board. Cut the boards to fit at the ledger, and trim the excess. A herringbone pattern also requires joists on 12-inch centers. Double every other joist so the decking joints meet on them at right angles. Measure from a corner to the first double joist, and mark this distance on the header. Lay the starter board at a 45-degree angle on this mark, and the next board at 90 degrees to the first one.
Cordless tools are convenient, but a variable-speed corded drill won’t stop you when batteries need charging. It will keep going as long as you do.
You can get a good idea where to drive nails or screws by watching the joist beyond the boards. But to line nails up consistently, lay a carpenter’s square against the decking and parallel to the joist.
If the nails you’re using tend to split the decking boards, and you can’t always drill pilot holes, try blunting the tip of each nail before driving it. This prevents most minor splits.
Use full-length boards where possible. Make sure joints butt together over the center of the joists, and nail 2×4 cleats to the joists under the decking. Staggering the joints will also increase their strength and greatly improve the appearance of the deck. To reduce squeaks and fastener pops, use a deck adhesive and spiral or ringshank nails or deck screws—two fasteners for 4-inch stock, and three for 6-inch boards. Drive the fasteners at a slight angle toward each other. Treated lumber is dense, so it may help to predrill it before putting in fasteners. If any wood is splitting, predrill it.