The Standard Grout Width for Porcelain Floor Tile

Recommendations

• The National Tile Contractors Association in conjunction with the American National Standards Institute and the Tile Council of North America have established standard recommendations for grout joint size. For every piece of tile in a same-sized batch there is an allowance of 1/16-inch variance in the face size before the grout joint needs to be increased. The minimum recommendation is for a 3/16-inch joint for every 1/16-inch size difference.

1-inch Tiles

• 1-inch tiles are sold in sheets, usually 1-by-2-feet, although 1-foot sheets are also sold. The average grout width on these sheets is 1/8-inch. If you are installing 1-inch porcelain tiles outside of a sheet setting, such as one at a time, you can adjust the joint width as you see fit, but the standard size for small tiles is 1/8-inch or slightly smaller, to accentuate the size of the tiles.

4-inch Tiles

• Many 4-inch tiles come straight from the manufacturer with built-in lugs on the sides, useful for what is known as wall stacking. With 4-inch porcelain tiles the grout joint width is generally around 1/16-inch, with the lugs on the side of the tile acting as a buffer between tiles that keeps the joint uniform while you stack the tile tight to one another. You can adjust this joint wider if you prefer.

12-inch Tiles

• The standard grout joint width for 12-inch porcelain tiles is at least 1/4 inch, with variations up to 3/8 inch depending on personal preference and the variation in face size. Twelve inch tiles are the most common sized tiles used, and while the average joint is around 1/4 inch, you can shrink the joint down to 1/8 inch if you prefer, although the size variations will be more noticeable.