What size mortar joint should be used with glass block?
Typically in straight flat walls both horizontal and vertical joints vary in width between inch and inch. Reinforced joints should not be less than inch, otherwise, the cross wires of the reinforcing could point load the glass block and cause breakage. In curved walls the inside vertical mortar joints should not be less than 1/8 inch wide and the outside vertical mortar joint should not be more than 5/8 inch wide.
