How to Build a Concrete Picnic Table

Make molds for the seating. Prepare a box-style mold by making a wooden frame of the desired seat dimensions. Add a plywood bottom to complete the box. Make the box frame deep enough to accommodate a 4-inch seat plus rebar mesh.

Make a mold for the tabletop. Prepare a box-style mold as you did for the seats, using the desired dimensions. A 4-inch-thick tabletop should be fine.

Pour in enough concrete to cover the bottom of the molds. Lay the rebar mesh down onto the concrete and continue pouring until the rebar is completely covered and the desired depth is achieved. Shake the molds to settle the concrete. Using the trowel, smooth out the top layer of concrete. Set for at least 24 hours, or according to cement package directions. Remove the concrete seats and tabletop from the molds after the drying period, by pounding with a mallet.

Dig 4-inch-deep footings to accommodate the concrete blocks that will support the tabletop and seat legs. Make two footings for the tabletop and two footings for each seat. You want the legs to be near, but not at the edge of the seats and tabletop, so measure according to your desired dimensions. Allow for rows of blocks that will support the heavy weights of the table and the seats.

Pour enough cement into the footings to hold the concrete blocks in place. Alternate stacking and cementing blocks together. Place blocks side-by-side in the footing, and stack three blocks high for the table and two blocks high for the seating. Use the trowel to spread cement to all sides and between the blocks. Insert rebar poles into the hollow centers of the blocks and add cement to fill the centers. The rebar should not extend beyond the top of the highest block.

Add an additional amount of cement on the top of each seat leg that will act as an adhesive for the concrete seats. Place the seats onto the legs and press them into place. Allow at least 24 hours to set, or follow the cement package directions.

Add an additional amount of cement to the tops of the tabletop bases to serve as an adhesive. Press the tabletop down onto the bases. Set for at least 24 hours or as directed.