ASK THE EXPERTS QUESTION I have a client with glass tiles crack- ing on an install. I have attached a few images he sent over to me. The GC admitted to not installing with a crack suppression membrane. They also drilled pilot holes for a door install that resulted in cracking. The tiles associated with the holes were installed before drilling. The final comment by the client was the cracking was from the back, and did not come through the face. In your opinion, is it likely the lack of a crack isolation membrane cre- ated the opportunity for all of these tile cracks? ANSWER It appears to me that the crack at the window wall may be related to structural stresses within the framing or deflection in the sub- strate. The crack at the control valve may be related to structural stresses such as deflection within the substrate that was not well supported at the valve location. The cracks from the drill holes are likely related to the physical and heat stresses placed on the tile dur- ing the drilling process and may also be related to deflection in the substrate if the substrate was not well supported in this area. A crack isolation membrane would likely not have prevented the cracking. There are other potential issues that can cause large-format glass tile to crack. They would include: Incorrect mortar or adhesive selec- tion; mortar cure time (which will vary based on the mortar used and whether a waterproof membrane was used); thermal expansion from light or hot water; lack of expan- Sponsored by 24 TileLetter | July 2017