Sundeck Simplified
Build a deck — without digging a hole
By:
Joseph Truini
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   (8.5/10) If you’ve always dreamt of building your own deck but could never quite find the time, then keep reading because your dream is about to come true. You’ll learn how to build a 12x16-ft. sundeck in just one weekend. Best of all, you won’t have to dig a single hole or mix up even a cup of concrete. The timesaving building technique used here is called a floating-foundation system. The deck isn't attached to buried posts or to a ledger board bolted to the house. The entire structure is supported by a series of pre-cast concrete piers that you place directly on the ground. For this deck, I used Dek-Block piers, which cost about $5 apiece and weigh 45 pounds each. The piers measure 8 in. high x 11 in. sq., and molded into the top of each one are 1 1/2-in.-wide slots and a 3 1/2-in.-sq. hole. The slots accept 2-by joists; the hole is for a vertical 4x4 post — required only when building on sloping terrain or to create multilevel decks. Here’s a brief description of the two-day construction sequence for this simple sundeck: Day 1
Plan to spend this day setting the 30 concrete piers into place and building the understructure framing out of pressure-treated 2x6s. The framing is supported by six rows of concrete piers laid parallel with the side of the house. The rows are spaced 25 ½ in. apart; each row has five piers. Begin by setting the four corner piers. Set the two corner piers near the house (photo 1). Space them 14 ft. on center so the 16-ft.-long floor joist will overhang each end by almost 1 ft. Place a straight joist into the slots in these corner piers, and then check the board for level. If necessary, dig dirt from beneath the high-side pier. Once the joist is level, remove it and position the three intermediate piers of that joist. Next, set the two corner piers farthest from the house. Temporarily lay a straight 2x6 between an outside corner pier and the closest of the corner piers near the house. Shift the outside corner pier left or right until the joist is perfectly square (90 degrees) to the house. Check the joist for level. If the outside corner pier is too high, dig out a little dirt beneath the base; if it's low by 2 in. or so, add gravel underneath. If you must raise the joist more than 2 in., cut a 4x4 post to fit between the pier and joist. Once the joist is level, install four intermediate piers (photo 2). Repeat this pier-setting process for the other outside corner. When finished, you should have three rows of piers: one along the house and one coming out from each side of the deck. Now install all the joists, level them and install the intermediate piers (photo 3). Next, screw a band joist across the ends of the floor joists at the left and right sides of the frame (photo 4). At the joist farthest from the house, screw on short outriggers, which are 12-in.-long 2x6s (photo 5). Install one at each of the five piers, and then attach the final band joist to the outriggers (photo 6). Check to be sure that the frame is square and that each joist is level. Once satisfied, backfill around any piers that were dug into the ground (photo 7).
Day 2
You’ll spend this day installing the 2x6 decking, which only took about 4 hours in this case. Start by laying all the 2x6 deck boards across the joists (photo 8). Butt the boards tightly together if they’re wet; as they dry, they'll shrink and a gap will form between each board. If the decking is dry, leave a 1/8- to 1/4-in. space between each plank. Align the ends of the boards along the house so there’s about 1 in. of space between the decking and the house siding. Then attach the boards with 3-in. galvanized screws (photo 9). Finally, snap a line across the outer ends of the boards and trim them straight with a circular saw (photo 10). Now, all you need to do is pick up the cut-off pieces, sweep off the deck and fire up the barbecue. Photos by John Nasta |