Installation methods for veneers fall into two general classifications: adhered and anchored. Thin veneer elements such as tile, thin brick and terra-cotta are often adhered to a solid substrate material, which is in turn attached to the building?s exterior structural wall framing with fasteners. Appropriately sized and spaced fasteners provide effective anchorage of the substrate with the adhered product when the adhesive materials bonding the face materials are properly prepared and applied.
However, when natural stone is used in veneer form using an adhesion installation method, there are a number of issues that will affect the performance of the installation. Building movement is a serious concern. Hard setting stone does not allow it to move independently of the structure. Therefore it must attempt to expand and contract at the same rate as the mortar, steel and other products that the building?s substrate and structural exterior are fabricated from. This will not happen, and the stone may spall or crown at the joints. This will stress or break the bond or it can fracture the stone, as the stone?s natural tendency to expand and contract at a given ratio is constrained by the installation method. Principles of cladding design require independently anchored stones and flexible stone joints 2 to 4 times larger than anticipated building movement to allow for this movement