How to Build an Open Vanity

Sketch a basic plan of the vanity. Label the height, width and depth. Typical vanity heights range from 30 to 36 inches, including the countertop, while the depth generally ranges from 18 to 24 inches.

Determine the thickness of the countertop material. Depending on the material, this may range from 1/2- to 1 1/2 inches. Add the material thickness to the plywood substrate thickness of 3/4 inches. Cut four 3-by-3-inch posts of the lumber to the desired height of the vanity minus this measurement.

Cut a 1-by-4-inch board to 5 inches in length. Rip in half again lengthwise to form two blocks. Repeat to create eight blocks total. These are spacers, one for each post at top and bottom. Each will actually measure 3/4 inch thick, 1 3/4 inches wide and 5 inches long.

Glue and screw the top spacers to the 3-by-3-inch posts. Align the spacer flush with the top edge and with one side of the post, leaving about 3/4 inch between the spacer and the opposite side of the post. Use one 1 1/2 inch screw on either end of the spacer.

Flip the posts over and measure up from the bottom 4 to 5 inches. Attach one more spacer per post to create the nailing surface for the bottom skirt.

Cut two 1-by-6-inch boards to measure the depth of the vanity less 5 inches, which is the actual thickness of the posts on either end. Make two additional 1-by-6 boards, this time measuring the total depth of the vanity less 1 3/4 inches. These are your top skirt and ledger. Repeat with 1-by-4-inch boards to create two lower skirts and two ledgers for the bottom shelf.

Spread carpenter's glue along the edge of the spacer on two posts at a time and attach the 6-inch skirt. Fit it down in the 3/4 inch space between the spacer and outside edge of the post so it sits flush with or slightly inside the plane created by the posts. Flip the posts over and drive two screws through the spacers into the back side of the skirt, taking care to avoid penetrating the outer skirt surface. Repeat with the 6-inch skirt on the opposite two posts.

Attach the lower two skirts using the 4-inch boards. To make the upper or lower skirts slightly recessed between the posts, which form the vanity legs, sand one face slightly before fitting into place. When complete, the posts couple into two sets of legs, each connected with a 6-inch-high skirt at top and a 4-inch-high skirt at bottom.

Flip the legs over and attach the ledger strips. Space the ledger 3/4 inch from the back edge of the rear leg and 1 inch from the surface of the front leg. Spread glue and secure with screws, countersinking them slightly below the wood surface.

Cut the side-to-side skirts from additional 1-by-6-inch lumber for the top and 1-by-4-inch for the bottom. Squirt glue across the ends of the ledger boards where the skirts attach. Countersink screws, driven through the face of the skirt into the ledger, to secure. Use a pocket screw jig to drive the screws through the ledger into the back side of the skirt, alternatively, if available. Pocket screws allow the screw to angle through the wood and avoid visible attachments.

Set the vanity right-side-up on top of a sheet of 1/2-inch plywood, cut to the depth and length of the vanity assembly. Trace around the legs, where they rest on the plywood. Cut out the outlined area to create the bottom shelf.

Make braces to support the shelf and countertop. Measure from the front skirt to the rear to determine the length of brace. Glue the ends and attach to the skirt with screws, countersinking the screws into the brace ends or attaching with pocket screws from inside. Shelves only need one brace, but heavy counter surfaces such as granite require a minimum of two braces spaced far enough apart to accommodate a sink.

Spread glue across the shelf skirt and ledger. Insert the 1/2-inch shelf plywood, fitting it around the legs. Reinforce the attachment with small screws at the corners and across the shelf edge.

Cut a sheet of 3/4-inch plywood to measure the vanity depth plus 1 inch and the length plus 4 inches. This allows an overhang at the front and sides. Use a template to cut the sink opening required before installing the plywood on top of the vanity to make sink installation easier. Finally, attach the countertop with screws through the corners and into the braces.