GYPSUM BOARD OR DRYWALL
PLYWOODThis product is used for floors and counter-tops. It is basically wood sheets laminated together with glue. Durable exterior grade that tends to resist moisture should be used as a backing for tile in "dry" areas only. Various companies manufacture plywood in a variety of dimensions. There are advantages and disadvantages with their use as a backing for tile. In no case should a wood product be used as a backing for tile that will come apart or delaminate when moisture is present. This type of plywood is commonly referred to as particle board. Look in the sections covering Floors and Counter tops for more on plywood and its use.
BACKERBOARDThis product is used for walls, floors, and counter-tops. Backer board is also known by the name it receives from its manufacturer. It is also referred to as CBU (cement backing unit). Cementitious boards are available in fiber reinforced or glass mesh reinforced and are made by various manufacturers. When a cement-based product is made into a relatively thin board (1/4" to 5/8"), the board would fall apart without reinforcing. Some manufacturers mix the cement with a reinforcing water-resistant fiber in the fiber-reinforced type. Other manufacturers encase the cement in a water-resistant mesh. They were developed to replace the practice of building tile backing out of mixed cement mortar. The boards come in a variety of dimensions ranging from 32" to 48" wide and 36" to 120" long. Each has different qualities and capabilities. For more discussion on this type of backing and its advantages/disadvantages go to the sections dealing with their intended use: Walls, CounterTops, Showers and Tubs.
MORTARMortar can be used for all ceramic and stone tile applications. This is the oldest and sometimes best backing or substrate to receive a tiled surface. Basically, this is cement mixed with sand, water, and sometimes hydrated lime in various ratios. Various manufacturers produce the ingredients either separately or in a pre-mixed condition. Regardless of the manufacturer, only certain types of cement and hydrated lime should be used for satisfactory results. Like the manufacture of tile, mortar products and their use are governed by standards and testing established by ANSI/ASTM. Cement is covered under ASTM C 150, sand under ASTM C 144, and hydrated lime-type S under ASTM C 206/ ASTM C 207. Water for the mortar must be potable or fit for human consumption. For more on mortar, look in the sections covering their use.