QUESTION

We've got a mall renovation project that has specified for the tile control joints to be an 1/8" to match the grout joint width. There appears to be some disagreement that the TCNA requires a minimum 1/4" for control joints for interior tile applications. Our control joints are to be placed at every 20-25' and the project has a full coverage CSM. Do you know if the 1/4" is the minimum or can the joints be installed as an 1/8" and still comply with industry standards.

ANSWER

ANSWER -

TCNA Handbook does say that movement joints within the tile assembly should be at least ¼” wide, but the current version of the handbook does indicate that if your movement joints are installed more frequently that you can make the joints more narrow.  They also reference ASTM C1472 for how to calculate widths of movement joints based on the coefficient of expansion of the materials and temperature fluctuations.  The TCNA Handbook is a recommendation, so the architect or engineer can specify otherwise based on their calculations using ASTM C1472.

If it is an indoor mall with porcelain tile then there should not be a low of moisture or thermal movements, but there are potential dynamic structural movements the tile is subjected to.  I think if you put in 1/8” movement joints every 12 feet or so and if the tile was installed correctly, you probably are ok.