What is the general rationale for spacing movement joints in long tile runs?

• A. To reduce grout thickness.
• B. To accommodate substrate movement and prevent cracks; spacing depends on tile size, substrate, and manufacturer guidance.
• C. To make tile removal easier.
• D. To allow air circulation.

Answer: (B)

Movement joints are placed to absorb movement of the substrate and tile assembly as temperatures and loads change. In long tile runs, materials expand and contract at different rates, and without joints, stresses build up that can crack tiles or grout. Spacing is tailored to the specifics of the installation—larger tiles typically require joints more frequently, and the substrate’s movement tendency plus what the manufacturer allows or recommends all shape the exact spacing. This guidance ensures the joints relieve movement effectively and safely. The other options miss the point: reducing grout thickness doesn’t address movement stresses, making removal easier isn’t the purpose of expansion joints, and air circulation isn’t a factor in why these joints are needed.