Which of the following is a potential drawback of using CBUs in tile installations?

• A. Weight
• B. Compatibility with mortars
• C. Easy installation
• D. No moisture concerns

Answer: (A)

Cementitious backer units are very dense and heavy, so they add a substantial dead load to the structure. That extra weight affects how the floor or wall is framed, can complicate transport and handling, and often increases labor and installation costs, especially on larger areas or above-grade installations. Other aspects—such as how they bond with mortars and the need for proper waterproofing—are manageable with standard tile practices, so they don’t constitute the same level of drawback. The idea that installation is easy isn’t accurate for CBUs, since they require careful cutting, fastening, and waterproofing steps. And while CBUs aren’t inherently waterproof, waterproofing membranes are typically needed to address moisture concerns. Because of the significant impact on structure and installation logistics, weight is the primary drawback.