Movement Joints & Expansion Joints Flashcards

Which TCNA specification number specifically covers movement joint requirements in tile installations?

Answer: EJ171

TCNA EJ171 is the industry-standard specification that defines movement joint requirements, placement, and materials for tile installations.

What is the minimum recommended width for movement joints in tile installations per TCNA EJ171?

Answer: 1/4 inch

TCNA EJ171 specifies a minimum movement joint width of 1/4 inch to allow adequate sealant performance and accommodate thermal movement.

For interior tile installations, what is the maximum recommended spacing between movement joints per TCNA EJ171?

Answer: 20–25 feet in each direction

TCNA EJ171 recommends movement joints at maximum 20–25 feet in each direction for interior tile installations to relieve built-up stresses.

Movement joints must be installed wherever tile abuts which type of surfaces?

Answer: Restraining surfaces such as walls, curbs, columns, pipes, and changes in plane

Per TCNA EJ171, movement joints are required wherever tile meets any restraining surface — walls, curbs, columns, pipes, or changes in plane — to prevent stress concentration.

What type of sealant is recommended for movement joints in wet or exterior tile areas?

Answer: Silicone or polyurethane sealant

Silicone or polyurethane sealants are flexible, waterproof, and bond to tile edges, making them the correct choice for movement joints especially in wet or exterior conditions.

What is the most likely consequence when movement joints are entirely omitted from a large tile installation?

Answer: Cracking, delamination, or tile lifting due to unrelieved thermal and structural movement

Without movement joints, stress from thermal expansion, moisture, and structural deflection has no relief path, causing the tile or mortar bond to crack, debond, or tent.

Movement joints located over structural building expansion joints should be:

Answer: The same width as or wider than the underlying structural joint

The tile movement joint must be at least as wide as the structural joint beneath it so the full range of building movement is accommodated without transferring stress into the tile.