240. It is very important that the walls of a building should be carried up as evenly as possible, no wall being built more than 3 feet above the rest unless separated by an opening. If one part of a wall is built up ahead of another, unequal settlement is produced. The joints in the brickwork of the higher part will have set before the remainder has been added, consequently the work laid last is very likely to settle away from the other. This not only weakens the wall, but also mars its appearance.

If it is absolutely necessary to carry up one part of a wall higher than the rest, the end of the high part should be stepped, or racked back, and not run up vertically, with only toothings left to connect it with the rest of the work.