Do You Have to Put Spacers in for a Slate Tile?

Size Variation

• Natural stone such as slate has wide variations in the size of the tiles, which means using spacers is difficult because no two pieces will ever be exactly the same size. The recommendation for grout joint width is that for every 1/16-inch variation in facial size, a minimum of 3/16-inch grout joint should be used. If you are dealing with slate tiles that have 1/8-inch variation in size, this can lead to a recommended joint width of 3/8 inch.

Walls Vs. Floors

• While spacers can be used in wall applications, they must also be accompanied by tile wedges to accommodate the variation in size between the tiles. The overall goal is to create a centerline that is used as a reference point for each grout line, and then have the overall tiles along that line average out in terms of grout joint width. For floor applications, spacers are pointless because you are using a grid rather than spacers to keep the installation square.

Importance of Grids

• Grid patterns on the floor are laid out prior to an installation and are square chalk lines that are a reference point for the slate tiles. Since slate tiles have so much variance in facial size, the grid lines are used as a reference point rather than spacers because there are no same-size tiles that can be stacked against each other using same-size spacers to control the joint width. Instead, a center line is chosen and the joints kept uniform along that line.

Jointless Installations

• While the joint width recommendations are there to help create a uniform-looking installation, grout joints are completely optional. If you choose, you can install slate tile with little to no joints between them, simply stacking the stone against the adjacent stones in a puzzle-like pattern. For jointless installations you do not need spacers, merely tile wedges to help make up for slight inconsistencies in size between tiles and only for wall applications where gravity will move the stones without help during the installation.