Brick Bonds
Bond in brickwork is the overlapping of the brick one upon the other, either along the length of the wall or through its thickness, in order to bind them together into a secure structural mass. It is true, mortar is used to cement the brick together into a monolithic whole, but the real bond is the overlapping of the brick which the mortar serves to maintain. Units are shifted back and forth so that the vertical joints in two successive layers or “courses” do not come into line; in other words, the brick are laid so as to break joint, the whole forming a natural bond or a structural unity giving strength to the wall.
The strength and rigidity of a wall due to this bonding are clearly shown in Fig. 46. A concentrated load at any point on the wall is thus distributed over a larger area as indicated by the dotted arrows.
Stretcher and Header
In speaking of brick bond, two terms are constantly recurring, viz., “stretcher” and “header.” When a brick is laid lengthwise of the wall, thus showing its long, narrow dimension or “face” on the surface, it is called a stretcher. If its length extends back into the wall, so that its short dimension shows on the surface, it is called a header. The stretcher secures strength in the length of the wall. The header serves to form the transverse bond, that is, the strength of the wall through its thickness. When a brick is broken, as the case may require, the fragment is called a “bat.” Bats are used either simply to fill in; or, as definite sized pieces, cut and used to make the bond come out right, in which case they are called “closures.” While at certain points of the wall bats may be necessary, they should be sparingly used and then only according to the best practices of the craft.
Design in Bonds
In the old days, and indeed up to comparatively recent times, brick bond was used only in a structural or natural way, that is, to secure the strength of the wall as a solid mass; but in the seventeenth century European builders began to see an artistic possibility in the bond as it appeared on the surface. They began to see the fine tracery of the mortar joint running over the background of the brick, which could be varied into attractive patterns by different arrangement of the brick bond. As a consequence, there have been developed, in the main, three different types of bond, Running or Stretcher, English, and Flemish, which are used at the present day, with various modifications, to secure attractive effects in pattern.
When, as compared with the past, the great variety of brick colors and textures now offered is taken into consideration, it may be realized what charming results may be secured in the wall surface by the combination of brick patterns, colors, textures, and mortar joints.
Running
The first and most obvious of these bonds is what is called Running or Stretcher Bond. The wall surface is made up of stretcher courses having at the corners a header which appears as a stretcher on the return side. This bond has the merit of being very strong longitudinally, but lacks transverse strength; consequently, it is modified into what is called Common or American Bond by laying a course of headers about every sixth course (Fig. 47). In order to maintain the effect of the running bond, a special double header bond is sometimes used as explained on page 19.
This method of using headers as in Common or American Bond, in order to secure transverse strength of wall, can be treated in a way to produce very much more pleasing effects, as may be seen in the English and Flemish Bonds.
English or Dutch
The English Bond is made up of alternating courses of stretchers and headers (Fig. 48). This produces a very pleasing series of Greek crosses and ripple lines up and down the surface of the wall, and the English brickbuilders claim for it the great merit of giving transverse strength to the wall. It however has a certain monotony that has lead to a modification which greatly beautifies it as a pattern, by breaking the joints of the successive stretcher courses (Fig. 49). This is called English Cross or Dutch Bond and results in a very attractive pattern in the wall of Greek crosses running in diagonal lines. The Dutch Bond differs from the English Bond only in the way the corners of the wall are treated.
Flemish
The Flemish Bond (Fig. 50) secures its effect by laying each course in alternate stretchers and headers, the header resting upon the facile of the stretcher in successive courses. This produces a very attractive pattern of inlaid Greek crosses and is a favorite among builders because of its artistic effect. It also may be modified in various ways by shifting the stretcher or header so as to produce different pattern effects, thus the Garden Wall Bond so-called (Fig. 51), is made by laying the courses with from two to four stretchers alternating with a header.
Figs. 47-51, illustrating the above bonds, are all drawn to show both exterior and interior corners of a wall, which is drawn as a two-brick wall at the left end and a three-brick wall at the right. The inside face of the three-brick wall in all cases is bonded to the middle tier by Common Bond. The method of starting the bond at the corner is clearly shown, whether by a quarter, half, three-quarter, or whole brick, also how the brick are cut or clipped, and how closures are used.
Face Brick Patterns
With these three fundamental bonds—the Running or Stretcher, the English, and the Flemish, innumerable other patterns may be made by the simple device of shifting the stretcher or header in successive courses back and forth, always breaking the joint, that is, never permitting two successive vertical joints to lie in the same line. To illustrate, we give examples of diamond-shaped patterns in Figs. 52 and 53 which are secured by a modification of the Garden Wall Bond. It is, however, only in case of large wall surfaces that patterns of an elaborate character could be recommended; ordinarily, the three bonds mentioned, with their simple modifications, will cover all requirements of domestic architecture. Simple patterns in brickwork may be made very attractive. Any departure from simple bonds adds to the cost of the bricklaying.
In addition to bonds proper and the patterns that may be woven out of them, there are certain other pleasing ornamental effects that may be secured in the wall surface by the arrangement of the brick. Thus for a water table or a sill course, the header or the stretcher may be set vertically. Treated in this way headers are called “row-locks” and stretchers, “soldiers” (see Figs. 44 and 45). For dadoes and friezes or for paneling, especially on large surfaces, patterns of a simple or ornate design may be used, as in Figs. 52-56.