DIY: Polyurethane Plywood Countertops

Attach 3/4-inch CD rated plywood to the cabinet base, using construction adhesive and 3-inch wood screws. Measure the length and width of the cabinet base, and add 1 inch around the perimeter to allow for countertop overhang. Apply construction adhesive to the cabinet base, and place the plywood down. Measure the overhang around the perimeter so that you have a consistent 1 inch.

Attach the plywood to the cabinet base with 3-inch wood screws, driving the screws into the cabinet's wood framing.

Cut cabinet grade plywood to the same length and width as the CD rated plywood. Apply construction adhesive onto the CD rated plywood with a caulk gun, and distribute the adhesive with a 1/4-inch notched trowel, making sure the adhesive completely covers the plywood.

Place the cabinet grade plywood over the CD rated plywood, aligning the edges. Then clamp the two together using wood clamps. Drive 1 1/4-inch wood screws from underneath the cabinet base and into the cabinet grade plywood on the top. Allow the plywood to set for 2 hours while the adhesive dries.

Install 1-by-2 hardwood strips around the perimeter of the plywood. Apply construction adhesive around the perimeter of the plywood, and attach the 1-by-2 strips to the edge. Miter the strips at the joints where extra strips need to be added. Align the strips with the top edge of the plywood, and clamp the strips in place with 4-foot bar clamps.

Attach the strips with a finish nailer and 2-inch finish nails. Fill the nail holes with wood filler, using a putty knife and filler to match the wood color.

Sand the plywood in graduated steps, beginning with 80-grit sand paper and ending with 120-grit paper. Sand in circular motions with an orbital sander. Apply one coat of water-based polyurethane to the plywood with a roller and brush, and allow the finish to dry for 1 hour. Sand lightly between coats with 120-grit sand paper to smooth the application. Apply three coats of gloss or semigloss finish.