How to Build a Small Wood Deck Over a Concrete Platform

Measure the width of the concrete platform with a tape measure to determine the size of the sleeper boards needed to base the deck planks on. Measure the length of the platform and divide it by 16 inches to determine the number of sleeper boards needed for the base. Make certain the number calculated allows for the placement of a board at each end of the concrete platform. The length of the platform always comprises the edge of the platform against any structures, so that the sleepers run perpendicular to any door openings, and the decking runs parallel to the opening across the tops of the sleepers.

Cut the required number of sleeper boards from pressure-treated 2-by-4-inch planks to the measured platform width, using a circular saw.

Drill pilot holes through the sleeper boards with an electric drill containing the same size drill bit as your hammer drive anchors. Space the holes every 16 inches along the board length, beginning about 1 inch from one end of the board. Position the holes down the board using a staggered placement pattern to avoid splitting the planks down the center.

Set the sleeper boards onto the concrete across the platform width, lying on the 4-inch sides. Place the two end boards along the edge of the platform, and then lay the intervening boards every 16 inches along the platform length, as measured from the center of the first end board.

Drill through the holes in the boards into the platform using a hammer drill with a carbide masonry bit the same size as your hammer drive anchors. Set the depth of the drill so that the holes in the concrete platform are 2 1/2 inches in depth. Remove each plank after drilling the holes, and use a wet-dry vacuum to vacuum out the concrete dust. Replace the boards onto the concrete with holes aligned after clearing the dust away.

Push a hammer drive anchor through each of the holes in the boards into the concrete by hand as far as you can. Drive the anchors the rest of the way into the concrete with a hammer. As you hit the pin on the anchor heads, an expanding flange at the bottom in the concrete will hold the bolt, and subsequently the board, in place.

Cut deck planks constructed of the hardwood of your choice to fit the length of the platform. If multiple planks are required, cut them in rows, using the discarded end of the last partial plank in the row to begin a new row of planking. This will give you a staggered placement of the planks, adding strength to the deck surface.

Set the planks across the sleepers, running perpendicular to the line of sleepers. If the deck is against a structure, position the first line of deck planks so that there’s a 1/8-inch gap between the planks and the wall of the structure.

Nail the planks to the sleepers with deck nails, using two staggered nails per sleeper. Butt the end of each plank in a row tightly together. After completing each row, measure a 1/8-inch space before laying the next row, to create a small expansion gap between rows. Continue with board placement until you reach the edge of the platform and the end of the sleepers. Cut the final row of planks lengthwise to fit along the edges of the sleeper using a table saw before nailing them into place.

Spray a layer of wood sealant over the deck to protect the planks against rotting and staining. Allow the sealant to dry for 48 hours before using the deck.