1.1 This guide covers unit sizes for clay and concrete masonry units laid in mortar for use in buildings and building systems designed in accordance with the principles of modular coordination. Specifically it covers:

1.1.1 Sizes of full-size units and supplementary units.

1.1.2 Joint thicknesses.

1.1.3 Specified dimensions.

1.2 Permissible variations from specified dimensions of masonry units vary with intended use, project requirements and type of product. Thus, permissible dimensional variations for masonry units should be obtained from the appropriate ASTM specification. See Section 2 for a listing of appropriate specifications.