Tile Grout Joint Standards

What is the standard for determining the size of a grout joint? We are often asked what is the standard for determining the size of a grout joint - can it be bigger or smaller - does it need to be a specific size, etc. There is a relevant standard. If you encounter low grout joints, you've encountered a situation that doesn't meet tile installation standards.

Refer to these tile industry resources. Extra care must be exercised when installing tiles with spacing lugs on the edge. Due to the amount of size variation in the tile, the actual grout joint width may need to vary from what is requested or specified.

The actual grout joint size should be equal to three times the variance in actual tile facial dimensions. The standards state that the grout joint width shall be at least three times the actual variation of facial dimensions of the tile supplied. The standards for calibrated porcelain tiles allow for about 1/16" size variation, so the grout joint width should be at least 3/16".

2.12.1 CAUTION: Exterior vertical sur faces in climates involving freeze-thaw conditions and high annual precipitation may require silicone rubber grout as joint filler between tiles, in lieu of cementitious grout. A general overview of how to respond to a client request for minimum grout joint by referring to the standards. Grout should be applied with a rubber float as close to the full depth of the joint as is practical - at least 2/3 of the tile thickness.

High ridges of setting bed adhesive or mortar should be raked out of the joint, prior to grouting, to insure uniformity of color of the finished grout joint. For running bond/brick joint patterns utilizing tiles (square or rectangular) with any side greater than 15", the grout joint shall be, on average, a minimum of 1/8" wide for rectified tiles and, on average, a minimum of 3/16" wide for calibrated (non-rectified) tiles. The choice of grout width for large format tile affects durability, appearance, and long-term performance.

This guide explains recommended large format tile grout size, industry standards, substrate movement considerations, and practical tips for installation and maintenance. What are the standards for grout joint widths and properly filling with grout? QUESTION We had marble tile installed with 1/16 inch grout lines and they vary from 1/16 to as much as 1/8. I am most concerned with the grout being very low, causing chips to the marble and also casting shadows so that the grout looks dirty.