How Thick Should Shower Tile Adhesive Be?

Mosaic Tiles

• Mosaic tiles are small pieces of tile that are 2 or 3 inches in diameter or facial dimensions. They can be round, square or random pieces of pebbles, but they are usually manufactured in some form of a sheet that is square or rectangular depending on the manufacturer. Mosaics never need more than an eighth of an inch of adhesive beneath them. More will result in excess squeezing up through the joints.

Walls

• The majority of wall installations use 12-inch to 14-inch tiles, with the notches on tile trowels for this size of tile ranging from 1/4 inch to 3/8 inch in depth. Both are acceptable for wall tile in your shower. Once the tile has been pressed into the adhesive, the actual thickness of the adhesive is around 1/8 inch or roughly half of the combed version after you spread it on the wall with a notched trowel. The actual notches of mortar spread out across the back of the tile, squishing or meshing together.

Polished Stones

• When you are installing polished tiles like marble and granite, the installation needs to be perfectly flat, in which case you can use what is known as a five-spot method of adhesive application. Five egg-sized dollops of adhesive are placed on the back of the piece on the outer corners with one in the middle, and then it is placed against the wall. After several pieces are stacked together, you use a level and rubber mallet to push the pieces against the wall and flatten the mortar so all the pieces are uniform with one another and plumb up the wall.

Large-Bodied Tiles

• There are always exceptions to the average, and some people prefer large-bodied tiles. These tiles are beyond 14 inches square, up to 24 inches square. Anything beyond 30 inches is generally referred to as slab material, not tile. When you are smearing adhesive for these tiles, you generally use a 1/2 inch notched trowel, although 24 inch tiles or beyond will need a 3/4-inch trowel. Once the tile is pushed into place, you will have 1/4 inch or more of compressed mortar holding the heavier pieces in place.