A platform-style wood deck that sits directly on the ground can be an attractive and useful addition to a walk-in garden or back yard. Build it on a level area, or as level as possible, and use concrete pier blocks to support the rim joists. In addition, use pressure-treated wood for the framing and a weather-resistant wood like cedar or redwood for the decking. If you want your deck to last, protect it from the elements with a high-quality stain, sealer or oil finish.
Level the area of the deck with a pick and shovel. Spread a plastic moisture barrier over the ground and secure it in place with 12-inch wire staples.
Dig holes at the corners of the deck perimeter and at 6- to 8-foot intervals in between for the pier blocks. These holes should be deep enough so that two-thirds of each block is underground. Use a torpedo level to make the surface of each block level and a line level to make all the blocks on the perimeter level with each other.
Set 2-by-8 pressure-treated boards on the pier blocks to form the perimeter of the deck. Connect these at each corner by using a drill to affix 2-by-8 corner brackets with 1 1/2-inch screws. Connect the wooden perimeter to each pier block by screwing an L-bracket into the wooden top of the block and screwing this bracket to the joist. If you have to join joists, do it at the midpoint of a pier block. Join them by screwing flat joining plates onto both members.
Use 1 1/2-inch screws to attach 2-by-8 joist hangers to two of the rim joists opposite each other at 16-inch intervals. Cut joists to fit in between these rim joists and drop them into the hangers. Screw them in with 1 1/2-inch screws.
Lay the decking boards on top of the frame, perpendicular to the joists, and screw them down with 3-inch screws. If you have to join two or more decking boards to complete the length of the deck, be sure they join at the midpoint of a joist. Use two screws per joist on each board.
Finish the deck with a wood preservative, stain or varnish.
When you join decking boards, you can make the joint more secure by scarf-cutting the boards. Do this by setting the angle of the circular saw blade to 45 degrees before cutting the boards to length. Set one angled board in place then set the other on top of it so the angles match. Screw the boards together into the joist to secure the joint.
Use goggles when cutting with a circular saw and keep your hands out of the path of the blade at all times.