Many times, when ceramic tile is installed, we, as installers, may not use all of the tile industry standards to our best advantage. These standards can be the installer’s best friend when assisting the consumer, whether residential or commercial, in deciding the grout joint size and pattern.

The attached photo illustrates the installation of a calibrated 6” x 18” woodgrain plank tile with a 33% offset and a small grout joint. The penny shown in the photo indicates the size of the grout joint which measures 1.52 mm, slightly less than 1/16”.

Now, let’s look at the American National Standard Institute (ANSI) requirements that apply to this installation. The standards listed have been edited to demonstrate only the part of the standards that are applicable to this installation, but does not alter or eliminate the overall purpose of each standard.

A108.01-2.6.2.2 in part states: For tiles with at least one edge 15 in. (381 mm) or longer, the substrate shall have a maximum permissible variation of 1/8 in. in 10 ft. (3 mm in 3 m) from the required plane, and no more than 1/16 in. variation in 24 in. when measured from the high points in the surface.”

A108.02-4.3.8 Grout joint size, in part states: “In no circumstances shall the grout joint be less than 1/16 in.”

A108.02-4.3.8.1 Running bond/brick joint patterns in part states: “For running bond/brick joint patterns utilizing tiles (square or rectangular) with any side greater than 15 in., the grout joint shall be, on average, a minimum of 1/8 in. wide for rectified tiles and, on average, a minimum of 3/16 in. wide for calibrated (non-rectified) tiles”. 

A108.02-4.3.8.2 Running bond/brick joint and any offset pattern, in part states, “For running bond/brick joint or other offset patterns (i.e., non-continuous grout joints) utilizing tiles (square or rectangular) where the side being offset is greater than 15 in. (nominal dimension), only patterns with an offset of 33% or less shall be specified.

The installers on this project had a really good quality calibrated (non-rectified) tile that had very little warpage. They followed the applicable ANSI standards; the floor was flat to 1/8” in 10’ and the pattern was a 33 % offset. But they didn’t meet the standard that called for a 3/16” grout joint with a calibrated tile. However, the items mentioned in the last sentence and their skill allowed them to successfully install this project with a 1/16” grout joint. Sometime this works, but every job is different, so don’t “assume” these conditions will occur in future projects. Do your homework, use these standards to your advantage, get paid for the quality work you provide, and be successful.