Instructions to Build Outdoor Concrete Countertops

Measure the dimensions of the base cabinet onto which you will install the concrete counter. Add 1 to 2 inches all around the edges for the overhang before recording the measurements.

Measure and cut two 3-inch-wide plywood strips to the recorded countertop length. Also measure and cut two 3-inch-wide strips to the recorded width.

Apply glue over the ends of a long strip and join the short pieces perpendicular to each end, forming square corners. Apply glue over the exposed ends of the short pieces and position the second long piece flush against these. This rectangular frame matches the countertop’s edges and serves as the template for the forms.

Lay this template on a 3/4-inch-thick melamine board and trace its outline. Set the template aside and cut over the marks on the board with a jigsaw. This board forms the base of the concrete mold.

Apply adhesive over the lower edges of the template before setting it over the edges of the melamine board. Allow the adhesive to dry for the time specified on the manufacturer’s directions.

Cut a section of mesh several inches smaller than the concrete mold base. Cut lengths of rebar to fit along the edges of the mesh piece. Wind lengths of rebar ties to secure the mesh to the rebar.

Spray the inner surfaces of the mold with a release agent. Mix quick-dry concrete with water in a bucket. Pour the concrete into the mold, ensuring it fills the corners evenly, until it is half full. Smooth out the surface of the concrete with a rubber float.

Place the rebar grid on the surface of the concrete. Continue to pour the remaining concrete in the mold, directly above the grid, until 1/4 inch inch from the top. Level the top of the concrete and leave it to cure for at least five days.

Slide the tip of a pry bar into the edges of the mold to loosen the concrete. Assign a helper to flip the mold over while you gently tap its base to release the concrete counter.

Spread masonry cement on the surface of the outdoor base where you want to install the countertop and place it directly above. Allow the cement to dry according to manufacturer’s directions.

Sand the surface of the counter with 200-grit sandpaper. Wipe away the concrete residue before applying a coat of outdoor concrete sealant over it.