How to Select the Trowel Size for a Tile

Determine the type of tile job desired. The sizes of trowel notches you need will depend on whether you are tiling walls where the tile hangs vertically, or floors where the tile will be horizontal, or both. The size of individual tile squares also will dictate the size of trowel needed. For smaller tiles up to 4 1/2 inches to be hung vertically, choose a trowel with 3/16-by-3/16-inch V-shaped notches. For larger wall tiles over 4 inches, use a 1/4-by-1/4-inch square-notched trowel. For setting large tiles over 16 inches, use a 1/4-by-3/8-by-1/4-inch square-notched or 1/2-by-1/2-inch U-shaped trowel for better adhesion.

Determine the material of the tile to be used, and note whether the back is very flat or slightly uneven or grooved. Each tile needs a good firm set against the wall back or sub-floor surface to prevent loose tiles down the road. Different notch shapes and sizes govern the amount of thin-set or mortar that remains and how it lies underneath to bond the tile to the surface. A larger tile between 4 and 16 inches with an uneven back, or made from a material such as porcelain that is not as absorbent, will require a 1/4-inch square or U-shaped notched trowel to insure that sufficient adhesive, thin-set or mortar is left behind for bonding. A 3/16- to 1/4-inch V-notched trowel will be sufficient if smaller mosaic or glazed tiles are used.

Choose the type of adhesive or mortar to use. Less absorbent tiles and kitchen or bathroom wall tiles work well with premixed latex adhesive, which may be spread with a 1/8 or 3/16 inch V-notched trowel. Floor tiles, on the other hand, often use a sanded thin-set or mortar, which works better with a 1/4-inch square or U-shaped notched trowel.