What is the purpose of expansion joints in tile work and where are they placed?

• A. To decorate tile borders
• B. To allow water to flow behind tiles
• C. To accommodate substrate and temperature movement; placed at changes in plane, at corners, and at intervals along long runs as per code/manufacturer.
• D. To increase grout lines; placed every four tiles.

Answer: (C)

Expansion joints in tile work are designed to absorb movement of the substrate and tile assemblies caused by shrinkage, settling, and temperature changes, so cracks don’t propagate through tile or grout. They must be located where movement is likely: at changes in plane such as where walls or floors meet, at corners, and at intervals along long tile runs, with exact spacing and placement following the local code and the tile manufacturer’s recommendations. These joints are typically filled with a flexible sealant or backer material, not with grout, to preserve the joint’s ability to flex. They are not decorative and they are not intended to increase grout lines or to create a path for water behind tiles.