Tile Expansion Joints 101

Movement joints, also known as expansion joints, are soft joints installed with a sealant in lieu of grout at specific intervals and perimeters to accommodate movement from thermal expansion and contraction.

While they may not be as important when tiling small single-surface areas like an entryway or tiled kitchen floor, they become critical when installing tile over large interior areas, exterior applications, or multiple abutting surfaces. Unfortunately, not installing movement joints is a major cause of tile and stone installation failures.

Where are Tile Expansion Joints Required?

The TCNA Handbook for Ceramic, Glass, and Stone Tile Installation, which is published yearly, contains method EJ171 Movement Joint Guidelines for Ceramic, Glass, and Stone. EJ171 is the industry standard guideline for movement joints, which lists all installation parameters. EJ171 key takeaways are that movement joints are required at:

Change in plane exterior, Change in plane interior
All expansion, construction, control, cold, saw-cut, isolation, contraction, and seismic joints (includes both horizontal and vertical surfaces)
Perimeter joints (where the floor meets the wall or adjacent floor or curb, column...)
Same plane movement joints
- Exterior – every 8’-12' in each direction
- Interior – max of every 24' in each direction
  - If direct sunlight, heat, or moisture – max 12' in each direction

Tile Expansion Joint FAQ

Can Substrate Joints Cause Cracks?

Yes. A common problem with movement joints is when a tile installation bridges over a joint in the substrate that has not been treated properly. This is often found on tiled flooring over concrete slabs that have cold or control joints installed within it. The tile that covers these types of joints can fail when a telegraphing crack occurs through the tiles and grout joints directly over the joint in the substrate. It's best to honor these joints in the concrete slab with soft sealant joints in the tile work directly over them or follow manufacturers' guidelines on anti-fracture products that will warranty bridging certain joints when treated properly.

Help! I don't have the required soft joints. What can I do?

Suppose a tile installation has recently been installed without movement joints. In that case, an installer can provide a quote to cut out the cement grout joints at proper intervals and replace identified joints with the appropriate sealant. It is recommended to do this as soon as possible, as improper or missing expansion joints can contribute to failed installations, such as the one shown below, referred to as "tile tenting." Tenting is also described as exploding tiles; there is no way to know when this might occur.

Does wall tile need expansion joints?

Yes, wall tile requires expansion joints and is not excluded from industry standards. Any change in plane or material requires a soft joint. This case study "shower cracked glass tiles" shows an installation where the absence of expansion joints may have caused or contributed to a failure. Some material is more prone than others to cracking, and may have custom installation requirements. Manufacturer recommendations should always be followed first, alongside industry standards.

Can I use acrylic caulk for a soft joint?

No, acrylic caulk is a soft plastic material consisting of pigment and a vehicle. It is used for sealing joints in buildings and other structures where normal structural movement may occur. However, acrylic caulk can harden and become a long-term maintenance issue, especially between planes.

What is the proper sealant to use in expansion joints?

The industry standards require that the sealant (caulking) that's used to caulk movement joints must meet ASTM C920. These sealants are silicones, urethanes, and polysulfides. Although they are easier to install, this does not include siliconized sealants, acrylic sealants, or latex sealants because they do not perform well. ASTM C920 designates sealants according to type, grade, class, and uses. Thankfully, there are many colors available in silicone-based sealants to ensure design continuity.

Silicone sealant is an elastomeric material that is used to fill and seal the expansion joint. Elastomeric means rubber-like (flexible) and can resume its original shape after being stretched or deformed.

Silicone sealant prevents moisture from passing through the expansion joint and allows horizontal and lateral movement.

Expansion Joint Standards

Earlier, we provided a brief, high-level overview of industry standards. Here are the details if you are interested in comprehensive information on the tile industry expansion joint standards.

ASTM Standards A108

A108.01

3.7.4.1.1: Suitable sealants include silicone, urethane, and polysulfide.
3.7.4.1.2 Tile edges to which the sealant will bond shall be clean and dry.
3.7.4.1.3 Install sealant after tilework and grout are dry. Follow the sealant manufacturer's recommendations.

A108.02-4.4 Movement Joints

4.4.1 Movement joints are required for overall construction, control, and expansion joints in the backing and where backing materials change direction, including terminations of tilework where it abuts restraining or dissimilar surfaces.
4.4.2 Movement joints are a requirement for tilework.
4.4.3Movement joints shall be kept free and clear of all setting and grouting materials.

The Tile Council of North America (TCNA) Handbook in EJ171 states the following:

Perimeter and field movement joints within a tile installation are essential and required.
Perimeter Joints-movement joints are required where tilework abuts restraining surfaces such as perimeter walls, dissimilar floor finishes, curbs, columns, pipes, and ceiling, and where changes occur in backing materials, but not at drain strainers.
Changes in the plane and interior-movement joints are required at all inside corners.
Interior–Perimeter joints, other than the perimeter walls, preferred not less than 1/4" but never less than 1/8".
Change in the same plane as the grout joint but never less than 1/8".