(1) CMU must be laid in a running bond pattern with the units in each successive course overlapping the joints in the course below. At corners the length of the corner unit must alternate direction on each successive course.

(2) The mortar must be sufficiently plastic and the units must be placed with sufficient pressure to extrude mortar from the joint and produce a tight joint. Joint furrowing must not exceed the thickness of the shell.

(3) Head joints of open-end CMU designed for use as bond beams that are to be fully grouted need not be mortared.

(4) Surfaces to be in contact with mortar or grout must be clean and free of deleterious materials.