The thickness of brick walls for dwellings not higher than three stories ought to be 12 inches, although 8 inches is considered by many experts to be quite thick enough for small houses. If the foundation walls are of rubble-stone they should be 8 inches thicker, and if of brick or concrete they should be 4 inches thicker. Usually the walls will be faced with some variety of face brick, in which case they should be bonded into the wall. If a running bond is used, the face brick should be bonded into the backing at every sixth course by cutting the corners of each brick in that course of face brick and putting in a row of diagonal headers behind them, and also using suitable metal anchors in bonding courses at intervals not exceeding 3 feet. Where Flemish bond is used, the headers of every third course should be a full brick and bonded into the backing. If the face brick is of different thickness to that of the common brick backing, the courses of the exterior and interior should be brought to a level bed at intervals of about eight courses in height of face brick, and the face tied into the backing by a full header course or other suitable method. [Illustration: FISKLOCK BRICK] FUNDAMENTAL BONDS IN BRICKWORK It is very easy to understand the bonds in brickwork if the fundamental forms are known. There are, in reality, but two real bonds: namely, the English and the Flemish bond. The so-called running bond is no bond at all; while the common bond is found only in common brick walls, and uses a bonding course of headers every sixth course. The Dutch bond is only a slightly altered arrangement of the English bond, and is produced by merely shifting the centring of vertical joints of the stretcher course. By arranging these fundamental bonds in varying manners a decorative pattern can be produced on the wall of brick. [Illustration: 15. Brick Joints] TYPES OF JOINTS Here, again, as in the stone wall, the mortar joint plays a great part in the final effect of the design. It can be safely set forth as a rule that the rougher the texture of the brick used, the rougher and wider should be the joint. For the smooth-faced brick the joint should be small and finished with a tool. For a rough-faced brick the joint should be large and rough in texture. The various forms of brick joints in common use are shown in the illustrations. [Illustration: 16. Lintel Construction] LINTEL CONSTRUCTION