Rectified tiles continue to increase in popularity, particularly in the commercial arena. For years, the industry and Dal-Tile have recommended that Rectified tiles can be installed with a 1/16" grout joint. However, from the contractor’s perspective, installations have become more time consuming and difficult to ensure compliant installations when attempting to install a Rectified tile with a 1/16" grout joint. In response, the new TCNA (Tile Council of North America) Handbook addresses this issue by recommending that the width of the grout joint used be determined by the ANSI A108.02 specification which states that the actual grout joint size shall be at least 3 times the actual variation of facial dimensions of the tile. To simplify: Rectified tiles, regardless of size, shall have a grout joint width no less than 1/8". As a result, Dal-Tile is changing its recommended grout joint width to be 1/8" for all of its Rectified tiles.
In addition, we will no longer recommend in our literature that Rectified and Non-Rectified large format rectangle sizes (Ex: 12" x 24") can be installed in a brickwork or running bond pattern where the overlap is 50%. The reason for this is that the allowable warpage for a tile based on ANSI specifications can create an installation issue when large format rectangular tiles are installed in a brickwork/running bond pattern. This allowable warpage can create a scenario where lippage is inevitable given the overlapping pattern. To mitigate this effect, Dal-Tile will be removing the brickwork pattern from our catalogs and literature. This will be replaced by a new pattern that will be referred to as a "Staggered" brickwork pattern where the overlap does not exceed 33%, and the grout joint width must be a minimum of 3/16".
Editorial Note: There are other rep groups that will provide statements about the suitability of the use of large format rectified tile with the 1/16th grout line. The issue at hand seems to be that the TCNA based its ruling on field experience with a broad selection of tile, whereas some vendors are confident that their quality controls are sufficient to allow for the much reduced "margin of error." Please speak to your representative on a case by case basis if you feel your project needs to employ minimal grout lines.