About Expansion Joints Required
The ceramic tiles in the cartoon do not look too happy. They appear to be smashed together, are starting to crack, and are pleading for, “a little more elbow room, please!” Well that is exactly what would happen if tiles were alive and could talk without movement joints in place. As “George” states in the cartoon, expansion joints must be installed in all tile and stone installations per method EJ171- Movement Joint Guidelines For Ceramic, Glass, and Stone as published in the latest TCNA Handbook for Ceramic, Glass, and Stone Tile Installation.
Perimeter and field movement joints within a tile installation are essential and required. A few key guidelines are as follows;
Location and Frequency of Joints
- Interior- maximum of 25′ in each direction.
- Exterior- 8′ to 12′ in each direction. More frequent joint placement may be required depending on materials and environmental conditions.
- Interior tile work exposed to direct sunlight (heat) or moisture- maximum of 12′ in each direction.
- Above-ground concrete slab substrate- maximum of 12′ in each direction.
- Perimeter joints- movement joints are required where tilework abuts restraining surfaces such as perimeter walls, dissimilar floor finishes, curbs, columns, pipes, ceilings, and where changes occur in backing materials, but not at drain strainers.
- Exterior- Width shall be a minimum 3/8″ for joints 8′ on center and minimum 1/2″ for joints 12′ on center and increased for substantial temperature changes.
- Interior- Perimeter joints at perimeter walls- not less than 1/4″ and commonly covered by tile trim, cove base, or shoe molding. Perimeter joints, other than perimeter walls- preferred not less than 1/4″ but never less than 1/8.” Change of plane- same as grout joint but never less than 1/8.”
- Suitable sealants include silicone, urethane, and polysulfide. Use sealants complying with ASTM C920, which designates sealants according to type, grade, class, and uses.
The guidelines stated above are only a few highlights from TCNA EJ171 so refer to the latest TCNA Handbook for the complete version.
Don’t make your tiles unhappy by not placing movement joints within your installation or you may just find that they crack under the pressure!