The increasing popularity of dimension stone as an exterior cladding material has been accompanied by some highly publicized problems. A comprehensive testing program is a useful tool to minimize problems with stone veneers. INITIAL TESTING The initial testing program should ascertain that the stone meets minimum ASTM material requirements and evaluate its durability. The ASTM test procedures for flexural strength, modulus of rupture, and compressive strength require that five specimens be tested for each of the various test conditions. FLEXURAL STRENGTH A property that must be known for the structural design of a stone veneer is flexural strength; it gives a good prediction of the behavior of a stone panel under wind loads on a building. ASTM C 880 measures this property. MODULUS OF RUPTURE Another measure of a stone's flexural strength can be obtained from ASTM C 99, the modulus of rupture test. COMPRESSIVE STRENGTH Compressive strength is tested in accordance with ASTM C 170. ABSORPTION AND SPECIFIC GRAVITY Absorption and specific gravity of stone specimens are determined in accordance with ASTM C 97. PERMEABILITY Though not yet established by ASTM, the permeability test is important for the design of wall flashing, drainage, and corrosion protection systems. It determines whether or not water can permeate the thickness of the stone. DURABILITY Though no standard ASTM test for environmental durability has yet been approved, Committee C 18 on Dimension Stone is now considering an accelerated weathering test.