The sandbox is 6 ft. by 6 ft. Two 12 ft long 2x12's can be purchased and each cut in half to provide the boards for the sides. Or buy four 8-ft boards and cut them to 6 ft long. The sides are joined at the corners with a corner post. Which is bolted to each of the boards at the corner.
For the corner post use a 2x4 cut 1 ft long and attach the sides to the corner post with 1/4 inch carriage bolts. The 2x12s can be nailed together first with 16-penny nails first to hold it all together before adding the corner posts. The sides should be secured with 6 carriage bolts per corner. The length of the bolts specified ensures they will no protrude through the wood. This will keep them from catching anybody in the back.
Nail the four side boards together. Then holding corner posts in place, drill the holes for the carriage bolts. First drill the ¾" countersink holes ½ inch deep in the corner post, then drill the ¼ inch diameter holes all the way through the post and the side boards starting inside the center of the countersink hole.
Install the bolts from the outside, that is through the side boards going in to the post. You will probably have to hammer them through. Install the washer and nut and tighten down firmly with a socket wrench.
OPTIONAL: The size can be made smaller (or bigger!) if you wish, just reduce the dimensions accordingly.
Description of how to build the corner seats:
The seats can be made from pressure treated 1/2 in plywood or better, from 1x4's.
Plywood: Cut a 1-ft wide strip off the plywood on the 4-ft length of the plywood. Cut it into 4 triangles with 1-ft sides.
Attach these to the corners using 1-1/4 in exterior wood screws
1x4's: Cut four corner pieces. These will be triangles made by cutting the board in two 450 angles. Attach these to the corners with four 1 1/2 in exterior wood screws. (Predrilling the holes in the 1x4 material will prevent the small boards from splitting. And cut four pieces 1ft 6 inches and secure these next to the corner pieces with 4 screws each. Trim the boards to fit flush with the sides.
Bill of Materials
- 2 2x12's 12 feet long. Sides
- 1 2x4 8 feet long Corner Posts
- 1 4x8 sheet of pressure treated plywood or half sheet 4x4 if available seats (Optional if making seats with plywood)
- 1 1x4 8 feet long seats (Optional if making seats with 1x4's)
- 12 1/4x5" carriage bolts, nuts and washers
- 12 1/4x3" carriage bolts, nuts and washers
- 32 1-1/2"exterior wood screws
- 16-penny twist nails
1 yard of sand (27 ft3 )
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