Rationale

The current standard uses Grade designations “Interior” and “Exterior” to classify thin brick according to their resistance to damage by freezing and thawing when saturated at a moisture content not exceeding the 24-h cold water absorption. However, the Weathering Index Alternative of 7.1.4 directs the user to Fig. 1 to determine if Grade Interior requirements are applicable. Figure 1 does not mention either Grade Interior or Grade Exterior and refers to Grades “MW” and “SW” for face exposures based on weathering index. The physical property requirements and exposure recommendations for Grades Interior and Exterior correspond respectively with those of Grade MW and SW face brick found in other clay brick standards. This revision replaces the Grade designations “Exterior” and “Interior” with “SW (Severe Weathering)” and “MW (Moderate Weathering)” to achieve agreement with Fig. 1, as well as grade classification consistency with other clay brick standards.