If it becomes necessary to stop building a wall, to be completed at a later stage, this can be achieved by toothing so later the new section can be bonded in and the whole appear as one continuous piece of work. The end of the wall is toothed by overhanging each alternate course, to the one below, by a distance equal to the lap. It is a practice to be avoided, if at all possible, as it is difficult to ensure a solid bed joint and a line of weakness can result.