With cabinet frames secured and in place, cut 1/2” or 3/4” plywood to the exact size of the countertop. Be sure that all plywood edges are flush with the edges of the cabinet frames and butt up correctly with the walls. A trim piece (“skirt”) of either wood or granite will be installed on the outside edge of the countertop after the granite tiles are in place.
With an electric drill and a screwdriver bit, secure the plywood to the cabinet frames with wood screws, making sure to push the heads below the plywood surface. Take care that all screws go directly into the cabinet frames.
Mark cut lines on the cement backer board. Use a skill saw with an abrasive blade to cut the pieces of backer board to fit right on top of the plywood.
With the notched trowel, evenly spread a thin layer of thinset on top of the plywood. Using drywall screws and an electric drill, countersink screws every eight to ten inches to secure the backer board to the plywood.
Starting from an outside edge of the countertop and working from that countertop edge back to the wall, dry fit the granite tiles on top of the backer board, positioning the tiles in as close an approximation to the desired finished layout as possible.
Make sure the tiles line up squarely to each other and that the grout lines are equal in width across the entire countertop. To make the tile surface look more like a slab of granite, use the thinnest spacers you can find. Set consistent grout lines.
Mark all tiles that need to be cut. Use the wet saw to cut the tiles and lay those tiles into place as well. Make any necessary cuts to fit the tiles around the sink, remembering that the fewer cuts the better.
Spread thinset on your backer board, keeping your trowel at a 45-degree angle to create substantial grooves (Image 1).
Again, mix a batch of thin-set mortar to a peanut-butter consistency. Let it set for several minutes after stirring. With the notched trowel, spread a slightly thicker layer of thinset than that between the plywood and backer board on top of the backer board.
Using drywall screws and an electric drill, countersink screws every 8 to 10 inches.
Set your tiles carefully onto the thinset and "wiggle" them into place (Image 2).
As you proceed with setting the tiles in the thinset, use a level to check your tiles regularly for accurate, level positioning (Image 3).
Make sure to use spacers between the tiles to preserve a straight grout line (Image 4). As with the laying out, use thin spacers to minimize the width of the grout lines (Image 5).
Once the thinset has dried, grout the granite tiles counter with an unsanded grout that matches the color in the granite tiles. The idea is to disguise the grout lines as much as possible to create the illusion of a granite slab. Apply with a sponge per manufacturer’s directions.
Depending on cabinet type, choose a tasteful skirt to form the edge around the countertop. Skirts around a granite-tile countertop are typically made of 1-1/2” to 2” wide granite pieces that exactly match the granite tiles or of wood that blends well with the look of the granite tiles. The idea of the skirt is to completely cover the edge from the top of the granite to just below the top of the cabinets