Wall Tile and Mortar Types

• While there were once a few standard sizes of tile that could be used on the walls of your home and one standard type of mortar to hold them up, there are now countless types of tile and multiple types of mortar. Before you can choose a trowel, you have to choose both your tile and your mortar. The size of the tile, from mosaic up to 16-inch, will have a big impact. So will the type of tile, since glass tiles actually require you to smooth out the mortar, not comb it, and 12-inch marble tiles will usually use a white thin set, rather than a mastic.
  
  

Trowel Sizes

• When you have your tile and adhesive on hand, it's time to choose the trowel. While there is a general guide to trowel sizes, there are also exceptions to every rule based on the type of tile and adhesive.
  
  For mosaic tiles made of ceramic, porcelain or stone, use a V-notch trowel in a size from 3/16 to 1/4 inch. The smaller the mosaic in this case, the smaller the trowel size. A 2-inch mosaic will take a 1/4-inch trowel, while a 5/8-inch mosaic will be better off with the 3/16. Once again, if you are installing glass tiles, even in mosaic form, the size of the trowel won't matter since you'll smooth out the mortar before installing the glass. You can also use a V-notch trowel with ceramic wall tiles up to 4 1/4 inch in size.
  
  For wall tile of all kinds (except glass) up to 8 inches in size, use a 1/4-by-1/4-inch square notch trowel. From 8-inch tiles up to 12-inch tiles of any kind, use a 1/4-by-3/8-inch square notch trowel. And for large format tiles of stone, porcelain or ceramic, use a 1/2-by-1/2-inch square or round notched trowel. The exception to the rule after glass tiles comes from the mortar. You can use a trowel on the smaller end of the scale with mastic; if you are using a thin set mortar, you can go up a size in trowel. Always go for the larger size, rather than smaller, if you are unsure.