We’ve all heard the phrase, “When in doubt – grout.” Most times we laugh when it is mentioned, but it certainly is not a best practice in the tile industry. Grout has a specific function and when used correctly, it does a great job. Unfortunately, too many tile placers (not qualified labor) seem to be unclear where grout is to be used and where it should not to be used.
Most grouts, by nature, dry hard and function well by filling the space between the tiles, offering a designer’s dream of color, as well as the required durability. However, grout is not the product of choice when it comes to tile changing plane or meeting a dissimilar surface. This is true in both cases when tile meets the bathtub.
The TCNA Handbook includes a large amount of information on the sealant materials as evidenced in the “B” section toward the back of the book. There are seven details shown for ceramic and porcelain tile installations and further back, there are seven details in the stone section of the Handbook. All of these details involve tile meeting a tub or shower receptor. Although the product used behind the tile may vary, all 14 of them requires, “flexible mildew-resistant sealant” which meets the requirement of ASTM (American Society for Testing and Materials) C920.
As was mentioned above, most grout products dry hard and will not tolerate much, if any, movement. When grout is used to fill the space between the tile and the tub, it will crack as soon as movement takes place. This movement can be caused by expansion from hot water, the weight of the water and the person using the tub, the materials used to construct the tub, and general movement within the structure. Whatever the cause of this movement, the result is an ugly crack, as seen in the attached photo.
The downside to this situation is that someone needs to handle this callback, most times for free. The repair/replacement involves very carefully removing the hard grout, vacuuming out the dust, and installing the sealant. The difficulty here comes when the installer uses the wrong product to replace the old grout. If an acrylic latex or siliconized latex caulking is used, it too, will dry hard and fail in a short time. The question is not when, but rather, how soon?
One final note. In order to do the job correctly, the only approved sealant materials listed under ANSI A108.01 section 188.8.131.52.1 include 100% silicone, urethane, and polysulfide. Using the appropriate sealant will eliminate these pesky call back issues and gain a happy customer.