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 your 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 necessary quantity of materials. Always purchase about 10 percent more than you estimate you will lay out; you will then have extra to account for cutting and breakage.

Preparing the Room
Remove any appliances, such as refrigerators, that abut your countertop. To shield the surrounding area, place a drop cloth on the floor and cloak cabinets with plastic sheeting.

A flush-mounted sink, which sits evenly with the countertop, should be installed before you move on to build your substrate, the solid surface your tile will rest on. A top-mounted (self-rimming) or under-mounted sink is installed after your new countertop is in place.

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

There are standard sizes for countertops—most kitchens have countertops that are about 25 inches deep with 4- to -6-inch backsplashes. 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 approximately one inch, and ensure that the front edge is ample enough to support the edge tiles. Install plywood pieces, facing the factory edge (the straight, precut edge your plywood came with) out toward the room. Attach the plywood to your cabinets with screws, checking to make sure the surface is level; install shims where necessary if 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 your tiles.