In a message dated 11/12/1999 8:29:20 AM Eastern Standard Time, [log in to unmask] writes: > Keep in mind thermal stress on the masonry as the sun goes past each day. On > a tower structure there is a twisting movement from sun heat. > > ][<en Ken, is twisting movement lateral or vertical? Do you mean a tower structure where height >= 4xwidth, or just any exposed structure? Your old friend, Chubby