Brick flooring doesn't visually work everywhere, but a kitchen is one place that often feels made for it. Long ago, ground-level kitchen floors were paved with actual full bricks, the way you would lay an outdoor patio, providing unmatched durability and fire resistance. Today, when you consider a brick floor, you're actually considering brick material cut to the thickness of standard floor tiles. (Flooring in full bricks would raise the room by several inches and potentially collapse your floor joists with the weight.) The process for laying brick-tiled floors is similar to that of ceramic, except the brick is stronger and harder to cut, requiring a wet saw. Also, since brick is porous, a final coat of tile sealer is required.
Start with a strong underlayment of heavy plywood or cement board. Remove all obstructions from the floor, including floor trim. Snap two intersecting lines across the floor to form four square sections.
Starting in one section, in the corner closest to the center of the room, spread out a few square feet of thinset adhesive with your tiling trowel. Press the first brick tiles into place along the lines you marked. Lay other tiles off the first ones, building out from the lines. Use your 1/2-inch piece of wood to estimate the spaces between them.
Lay as many full tiles as will fit in the room. Let them set for about two hours, then go back and install the pieces at the edges of the room and any other spots that require cuts. Make the cuts using your wet saw. Lay the cut tiles as before, making sure the cut sides are facing the wall and the factory sides are facing each other.
Let the tile set for day. Put one light coat of tile sealer on the faces of the brick with a sponge-brush, trying not to let it seep over into the lines between the bricks. Let the sealer dry for a day before you grout.
Mix and apply your grout according to the instructions it came with, pressing it into the lines with your grout trowel. Work in sections, letting the grout sit for a few minutes at a time, then wiping down the surface with a damp sponge. The coat of sealer you put on the brick earlier will help prevent the grout from staining the brick face.
Let the grout dry for several days, then seal the whole floor with your tile sealer.