Due to the increased use of stone in homes, builders have had to adjust the way that their homes and structures are designed and built beneath the stone application. Traditionally, it has been taken for granted that the structure beneath the stone areas could be the same construct that is beneath the hardwood, resilient or carpeted areas. With the increase in popularity in large-format stone and longer spans for larger rooms, failures can occur if the structures are not designed properly. Usually, builders rely on their in-house design team, architects or even the lumber and framing supply houses to provide them with the plans and designs for the construction of their homes. While this may be suitable for most of the areas that receive the common flooring types (carpet and wood), the areas that receive stone must be designed to a more rigid standard.
Deflection is the potential movement that the installation can experience when subjected to load and use. Stone requires a very rigid substrate in order to function correctly. Typically, substrates must meet the industry-standard maximum allowable deflection rating of L/720 for stone applications. Some adhesive manufacturers will allow an L/480 deflection standard for stone applications.