Tiling a countertop is not difficult, but it does take a fair amount of preparation. The keys to success are carefully calculating measurements, protecting the surrounding surfaces, and building an appropriate substrate upon which to set the tiles.

Making calculations. First, measure the length and width of your countertop to calculate how many tiles you will need. Remember to take into account special- sized tiles such as bullnose-edge and backsplash tiles when figuring out the quantity of tiles needed. Always purchase about 10 percent more so you will have enough after cutting and potential breakage.

Preparing the room. Remove any appliances, such as refrigerator and oven range, that abut the countertop. To shield the surrounding area, place a dropcloth on the floor and cloak cabinets with plastic sheeting.

A flush-mounted sink, which sits even with the countertop, should be installed before you build the substrate. A top-mounted (self-rimming) or under-mounted sink should be installed after the countertop is in place.

Building the substrate. You will need to create a level, moisture-resistant surface to support the tiles. Usually, this substrate will comprise a 1/4- to 1/2-inch sheet of cement backerboard layered over 3/4-inch plywood. (Although some pros suggest that layering your tile over a pre-existing laminate countertop is a possibility, it is usually best to just build your own substrate to ensure the durability and lifespan of your new countertop.)

There is a common standard size for most countertops—25 inches deep with a 4-to-6- inch backsplash. However, you may choose to alter the dimensions of your substrate slightly if doing so means you will have to cut fewer tiles.

When cutting the plywood, note that it should extend beyond the base cabinets by about 1 inch, ensuring that the front edge is substantial enough to support the edge tiles. Install the plywood, facing the factory edge (the straight, precut edge) out toward the room. Attach the plywood to the cabinets with screws, checking to make sure the surface is level; install shims where it is not.

Mark your measurements on the backerboard with a scribe tool or sharp knife, and then simply snap the material apart. Affix the backerboard to the lower layer of plywood with galvanized screws. Apply thinset mortar over the screw heads and fiberglass mesh tape over the seams where sections meet to create a smooth surface for the tiles.