Laying Out Countertops
Countertops are everyday work surfaces and are often subject to up-close scrutiny. Small misalignments can grow in importance if you have to stare at them all the time, so take the time to get your layout perfect. Most countertops are small enough that you can do a full dry run with loose tiles before starting the installation. Try to place equalsized cut tiles along the sides and back. If the back wall is uneven, make the adjustment with the cut tiles at the back.
Tools: Drill, level, square, and circular saw or saber saw.
1. Install a plywood surface. The countertop substrate should be at least one layer of 3/4-inch exterior plywood. Take care that the front edges are square, and parallel to the walls. Level the whole top. Attach the top with construction adhesive and screws
2. Waterproof the substrate. For a fully waterproofed installation, add a waterproofing membrane (15-pound felt paper or 4-mil polyethylene), followed by backerboard. Seal the joints of the backerboard with fiberglass-mesh tape, filled with thin-set mortar.
3. Lay the job out. When laying out an L-shaped countertop, start at the inside corner and plan to use full tiles there. Align field tiles with the edge of the substrate unless you plan to use edging trim tiles, in which case draw a reference line separating trim from field tiles. If possible, plan so that grout lines will be evenly spaced from the sides of the sink. Run cut tiles around the back edges along the backsplash.
Using an Existing Countertop As the Substrate
■ If conditions are right, you can tile over an existing laminated (such as Formica) countertop. The top must be square edged; a post-form countertop (with rounded edges) will not work. And it must be in sound condition, level, and firmly connected to the cabinets.
■ Remove the backsplash. Sand the entire surface thoroughly— use an electric vibrating sander, or spend a good deal of time hand-sanding with a sanding block and 60-grit sandpaper.
4. Mark the sink cutout. Determine where the sink can fit into your sink base cabinet. Flip the sink upside down and trace the outline. Remove the sink and draw a cut line an inch or so inside the outline. Some new sinks come with a paper cutting template that can be used instead.
5. Cut the hole. You could simply cut the opening with a circular saw, starting with a plunge cut, but cutting through backerboard with a circular saw will make a huge cloud of dust. So use a saber saw instead. Drill holes just inside the cut line at each corner. Use a drill bit large enough to match the radius of the sink corners. Use a saber saw equipped with a rough-cutting blade to cut the sink opening. Have extra blades on hand; you’ll probably need them. Install the sink before or after tiling, depending on the type.
Sink Options - If your countertop tiling project involves a sink, be sure to buy the sink and learn how it is installed before you set any tile. The most common type of kitchen sink is “self-rimming.” Install it after the countertop has been tiled; the edges of the sink rest on top of the tile. Install a flush-mounted sink before tiling, and run the tile up to the edge of the sink. Underhung sinks are difficult to install, but perform well. Neither a flush-mounted nor an underhung sinks has a lip, so messes and water from the countertop can be wiped directly into the sink.