Installing tile over a wall is a complicated process no matter where the tile is installed. Installing tile over a wall outdoors is even more difficult because of temperature and weather considerations. Since tile has very little natural movement, changes in temperature and moisture will create cracks or breaks in the tiles unless an expansion joint barrier is added to allow the tiles some flexibility during temperature changes. This, combined with practical installation tips will help any outdoor tiles look good for years.
Install a cement backer board over the wall where you want to install the tile. Use a drill to drill holes every 12 inches along each side of the backer board and on the wall where it will attach. Use the power screwdriver to screw concrete screws through the backer board and onto the wall. Cover the entire wall with backer board.
Spread a layer of polythene filler over the backer board, to a thickness of about 1/4 inch.
Cut the metal lath reinforcing wire to fit over the backer board, completely covering the wall. Slip a washer over the head of each nail, and nail the metal mesh to the walls with the powder actuated nails and a nail gun. Place a nail every 24 inches on all sides.
Mix some wall mortar until it has the consistency of thick mud. Spread the mortar over the lath until it is impossible to see the metal. Scratch the surface of the mortar with sharp objects to ensure the tiles stick to the surface. Allow the mortar to dry for 24 hours. Place a 1/4-inch thick layer of cement adhesive over the mortar to hold the tiles in place.
Place an hourglass shape of flexible adhesive caulk to create expansion joints every 12 inches apart on the wall before placing any tiles. This flexible material allows the tiles to shift with temperature changes without the tiles falling off the wall and breaking.
Press the tiles tightly into the wall and allow to dry for 24 to 48 hours. Fill any cracks between the tiles with additional adhesive caulk and allow to dry for 24 hours. Do not allow anyone to bump into the wall during this curing period.