Visit My

Amazon

Tool Store

The back buttering of tiles is a process of filling in the voids on the back of the tile with thinset mortar prior to setting the tile into place. There are a number of reasons for back buttering tiles. Whenever possible, however, it is preferable to apply the thinset mortar directly to the substrate material and to then place the non-back buttered tile into the thinset mortar.
 
One reason for back buttering tiles is that it is not always easy to trowel thinset mortar into hard to reach places, such as under the edges of kitchen countertops.

Back buttering tiles that will be located in these hard to reach places eliminates the need for troweling thinset mortar onto the substrate in these difficult spaces. For this particular situation, it is best to use a notched trowel and to apply a liberal amount of thinset mortar to the back of the tile prior to placing it on the substrate.

Back buttering tiles is also done to avoid lippage between neighboring tiles. For example, if there is a situation where one tile sits higher than another it may be necessary to back butter the lower sitting tile to raise it to the height of the neighboring tile. This type of situation can commonly arise at backer board joints and taped seams.
 
Back buttering tiles is a time consuming process, and as already mentioned, it is preferable to apply thinset mortar to the substrate rather than the tile itself. Consequently, back buttering tiles should be done on a case by case basis.