Mounting a countertop onto a wall gives the countertop an appearance of floating, as you are not supporting the countertop with base cabinets or legs. This is a convenient way to mount a countertop at any height. You can purchase brackets to hang your countertop from a wall, but using a few items from a home improvement store or hardware store can save you a significant amount of money.
Slide a stud finder over the wall to locate the wall studs. Mark each stud location.
Measure from the floor to the height you want the top of your countertop to sit. Place a mark on the wall at the height location. Subtract the thickness of the countertop and place a second mark for your brace board beneath the first mark.
Place a 2-inch-by-4-inch-by-6-foot wood board on the lower line you marked on the wall. Drive one or two 3-inch wood screws through the board and into the wall studs, using a drill with an appropriate screwdriver bit. Check the board and make sure it is level or adjust until it is level. Drive additional wood screws through the board and into the wall studs.
Attach three 1-inch-by-4-inch wood boards to the wall brace board to hold the countertop. Cut the boards 2 inches shorter than the depth of the countertop with a circular or table saw. Use galvanized heavy-gauge steel 90-degree L-brackets and 3/4-inch wood screws to secure the 1-inch-by-4-inch boards flush with the top of the board you secured to the wall. Do this at the ends and the middle of the 6-foot wall brace board. The 1-by-4 boards need to be placed above the wall studs, so some minor adjustment at both ends and the center may be necessary.
Measure 20 inches down from the 2-inch-by-4-inch brace board you attached to the wall and mark the measurement on the wall. This measurement must line up over a wall stud and directly beneath the 1-inch-by-4-inch boards you attached to the wall brace board previously.
Attach a galvanized steel adjustable 45-degree hanger to the wall stud at the 20-inch mark using 2-inch wood screws. Place a mark 18 inches out from the wall on the 1-inch-by-4-inch boards you attached to the wall brace board. Measure the distance from the 18-inch mark on the 1-inch-by-4-inch board down to the 45-degree hanger. Transfer that measurement onto a 2-inch-by-4-inch wood board and cut the ends of the 2-by-4 at a 45-degree angle, tapering both ends toward one another, making a trapezoid.
Attach one end of the 2-inch-by-4-inch board into the 45-degree hanger using 1/2-inch wood screws. Attach the other end of the board to the 1-inch-by-4-inch board by driving two 1½-inch wood screws through the top of the 1-by-4 into the 45-degree angled end of the 2-by-4.
Run a bead of heavy-duty project glue along the tops of the wall brace board and the 1-inch-by-4-inch boards. Lay the 6-foot countertop onto the boards. Drive two or three 1-inch wood screws up through the 1-inch-by-4-inch boards and into the underside of the countertop.