Tile assemblies move – accommodate them in your installation with movement joints
The subject of movement joints in ceramic tile installations occurs quite frequently on technical hotlines as well as on social media, especially when an installation fails. Some folks understand the importance of accommodating the anticipated movement of the tile assembly by installing them correctly while others do not. A statement that I have used for years but is not included in the Tile Council of North America (TCNA) Handbook may offer some insight. That is, “Movement joints are probably the least used, often misunderstood, but the most important listing in the Handbook.”
The consequences
Unfortunately, sometimes tile installers forget to allow for the anticipated movement, may not be aware of the importance of movement accommodation, or the job did not include any direction or specification for the movement joints. However, this is no excuse, since including them in all tilework is the installer’s responsibility. To help installers obtain help, guidance, and the required hands-on techniques, the National Tile Contractors Association (NTCA) Workshop programs can help (www.NTCATraining.com). At many of these programs, trainers demonstrate sealant joints and actively encourage attendee participation. This free training can mean the difference between success and failure.
Without movement joints, failure can, and many times will occur, resulting in what is known as tenting. See image #1. This sad situation happens when the area the floor or wall occupies is compromised by structure movement, a heat source such as sunlight or an in-floor heating system, or moisture. A tented tile job may be “temporarily fixed” by removing the loose tiles, preparing the substrate, and resetting the tile, but the success of this trick is fleeting since the installation still has no room to expand. The only way to permanently correct the problem is to remove all the tile, prep the substrate, and install the new tile with the appropriate perimeter and/or movement joints within the body of the tile installation. No matter how you look at this scenario, it is financially devastating. This is where the installer and the tile industry get another black eye.
The standards
The American National Standards Institute (ANSI) and the Handbook provide the following standards, methods, and best practices presenting numerous remedies.
- The ANSI A108.T [Terms] defines a movement joint as, “A construction joint, contraction joint, control joint, expansion joint, isolation joint, or any other type of joint designed to accommodate movement.” Following this ANSI statement is an explanation of each type mentioned, how they function, and how they are formed.
- ANSI A108.02-4.6 Movement joints in tile work states, “Movement joints are required for tile work in vertical and horizontal surfaces in interior and exterior applications.” Given this statement alone, which does not allow any room for discussion, it seems odd that tile installers would jeopardize their work by not utilizing movement joints, especially in exterior projects where the heat of the sun and moisture can precipitate movement.
- The Handbook section EJ171 reinforces the ANSI standard by stating the following. “Perimeter and field movement joints as seen in image #2, within a tile installation are essential and required.” In image #3, you can see the results of applying grout at an inside corner. The grout dries hard, does not allow any movement, and will crack. That is a callback that comes out of the installer’s pocket.
Design professionals determine joint placement
The Handbook also explains who is responsible to design and locate movement joints by stating in part, “the design professional or engineer shall show the specific locations and details of movement joints on project drawings.”
This statement clearly indicates that the tile installer is not responsible for this process but he or she will be expected to install these joints in the tile assembly using the appropriate back up (backer rod) and sealant. The EJ171 Materials section declares, “Back up strip shall be a flexible and compressible type of closed-cell foam polyethylene, butyl rubber, or open cell and closed cell polyurethane, rounded at surface to contact sealant, as shown in the details, and recommended by sealant manufacturers. Suitable sealants include silicone, urethane, and polysulfide.”
In grout joint or through the tile: movement accommodation is still needed
Movement joints have historically followed a grout joint, when possible, but many times the required joint was not close to a grout joint, resulting in the movement joints being cut through the tile pattern as shown in image #4. Often designers have balked at this process saying that cutting the tile will ruin the pattern and are unattractive. However, in recent years, new sealant joint patterns have been evaluated and found to work effectively. EJ171M shows examples of non-linear movement joints per ANSI 108.01, figure 11 pictured in image #5. These illustrations display a rectangular tile installation with a 50% offset, a movement joint in a diagonal tile pattern, and lastly, a 33% or 1/3 offset.
Using the ANSI documents and the Handbook methods and details to accommodate the movement of the tile assembly will yield a successful tile installation that will provide excellent service for years to come.
Scott Carothers
Scott Carothers is the Acdemic Director for the Ceramic Tile Education Foundation (CTEF) and is responsible for the creation of the Certified Tile Installer (CTI) program, and is involved in the creation of the Advanced Certifications for Tile Installers (ACT) program as well as providing training to others in the tile industry.
Carothers has been involved in the ceramic tile industry for nearly 40 years and was the owner of a successful retail and installation firm prior to CTEF. He has served as President and Chairman of the Board of the National Tile Contractors Association (NTCA), Chairman of the NTCA Technical Committee, was named the NTCA Tile Person of the Year in 2005, and the NTCA Ring of Honor recipient in 2013. He is a voting member of the ANSI and the TCNA Handbook committees.
