Since our tiles are not baked in an over or fired in a kiln they do not shrink or expand, which means they can be installed with or without grout. Although it is a personal preference, most customers choose to use grout on floor installations. Please note, standard grout is not recommended for use with cement tiles as it contains color pigments that are prone to stain the tiles. Please refer only to our suggested quartz-based grout list. The only instance where grout is strongly suggested is any application in direct contact with water. This is done to avoid any mold issues caused by water permeating through the joints and damaging the surface behind the tiles. Whether installing with or without grout, we strongly urge the use of a membrane to prevent tiles from cracking if there is any shift in the foundation.