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.
[Illustration: Fig. 46. Bonding Strength]
[Sidenote: 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.
[Sidenote: 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.
[Sidenote: 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.
[Illustration: Fig. 47. Common or American Bond]
[Illustration: Fig. 48. English Bond]
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.
[Sidenote: 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.
[Illustration: Fig. 49. English Cross or Dutch Bond]
[Illustration: Fig. 50. Flemish Bond]
[Illustration: Fig. 51. Garden Wall Bond]
[Sidenote: 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.
[Illustration: Fig. 52 Fig. 53 Diamond Bond Patterns]
[Sidenote: 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.
[Illustration: Fig. 54. Checkerboard Pattern]
[Illustration: Fig. 55. Basket Weave Pattern]
[Illustration: Fig. 56. Herringbone Pattern]