Minimum Spacing for Grout

Recommended Grout Width

• While the actual recommendations vary depending on the installer, the Tile Council of North America, the National Tile Contractors Association and the Construction Specifications Institute have set some guidelines for the best joint width. The rule stipulates that for every 1/16-inch difference in size for a same-size piece of tile, you should use at least a 3/16-inch grout joint to hide the size variance.

Polished Marble and Granite

• Polished marble and granite are meant to be installed tight to one another, with no more than 1/8-inch grout joint between the tiles. The preferred grout joint width is 1/16-inch, with the beveled edge of the tile adding an extra 1/16-inch visually, making for a 1/8-inch joint when everything is completed. However, variations in size can create problems that require you to space the tiles 1/8-inch apart to help hide the size differences.

Unfinished Natural Stones

• Tumbled marble and natural stone such as slate have large variations in size from tile to tile. A typical 12-inch tile can sometimes have variations of up to 1/4-inch, in addition to the tiles often not being square since they are quarried and not man-made. You should never use less than a 1/4-inch grout joint with unfinished natural stones because the size issues will be readily apparent with smaller joints.

Color Combinations

• Color combinations can help or harm a tile installation. For example, a dark grout against a light tile will make any variations in size readily evident, which means you will want to use a larger grout joint, such as 1/4-inch with a 12-inch tile for regular ceramic or porcelain. Light grout with a light tile, on the other hand, will hide the imperfections, allowing you to use a 1/8-inch grout joint, for example, without worrying about the size differences being visual.