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Ceramic, porcelain, and stone tile expands and contracts with thermal and moisture changes in the environment as do all building materials. The expansion or contraction will rarely be seen with the naked eye. However, it is still present. As we know from previous sections, stone, porcelain, or ceramic tile is very sensitive to movement. It does not take much movement to cause a failure in these tile installations. Ceramic, porcelain, or stone tile can shear, buckle, and break as a result of improperly placed or designed expansion joints.
The most common location of expansion joints is in large expanses of tiled floors. The width of a tile installation can result in the necessity of a joint. That means the tile will expand and contract one tile to another. Also, ceramic, porcelain, or stone tile installations need to be isolated from adjoining hard surfaces and between the tile and dissimilar surfaces. Expansion joints are necessary in both horizontal and vertical installations.
Most of us have seen expansion joints in use in various places. This section is designed to educate the reader on the various joints and point out that expansion joints are not just in floors.
ANSI, under sections AN 3.4 and AN 3.7 together with common industry practice, recommends expansion joints in tile installations at the following distances:
- Interior applications require joints at 24-36 feet on center
- Exterior applications require joints at 8-12 feet on center (*New for 2003). The width of the joint needs to be 3/8" for joints spaced 12 feet on center and 1/2" for joints 16 feet on center.
What is the reason for the difference?
Exteriors are exposed to more thermal and moisture differences. Some interiors have direct sunlight and need to be treated as exterior applications in the area of expansion joints. For example ANSI Recommends in AN 3.7.3.1 that interior tiled areas that are in direct sunlight have joints spaced 8-12 feet on center.
When we examine the measurements, it appears that most interior applications will not require expansion joints within the field of tile. While that is true of expansion joints within the field of tiled installations, it is not true for all types of expansion joints.
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