The first step of your woodworking project is to make the frame of the deck box. As you can see in the image, we recommend you to use 2×2 and 1×4 lumber for the frame of the box. Dill pocket holes at both ends of the slats and insert the screws into the legs.
Build the bottom of the deck box out of 3/4′ plywood. Cut the component at the right dimensions and drill pocket holes along the sides using a jig and a drill machinery. Fit the piece to the deck box and insert 1 1/4″ screws into the supports.
Glue and nail the side trim flush with the edges of the box end. Repeat for the opposite end. Measure between the two side trim pieces and cut the back trim (L) to length.
If you are going to use the wood as a planter box, drill 4 to 6 holes at the bottom of the box, especially the central plank. They should be ¼” in diameter. This allows any excess water to drain from the soil of your plant.
How to Build Waterproof Pool Deck Boxes for Storage ... Use nails to secure it there, wiping away excess glue inside and outside the box. Leave the glue to dry.
Set the lid back on top of the box and secure the hinges to the back of the box. Once the project is fully assembled, paint it or finish it with a waterproof sealer. Then, place the waterproof pool deck box on top of the concrete blocks to complete the job.