243. The proper construction of a brick building involves many things besides the mere laying of one brick on top of another with a bed of mortar between. The manner of laying or bedding the bricks and the general methods of doing the work having been considered, we will next consider the points in construction required to obtain a strong and durable wall, and the precautions to be observed to prevent settlements and cracks and adapting the work to the purposes for which it is intended.
Aside from the quality of the materials and the character of the work, the bonding of a wall has the most to do with its strength. Bond. - Bond in brickwork is the arrangement of the bricks adopted for tying all parts of the wall together by means of the weight resting on the bricks, and also for distributing the effects of a concentrated weight over an ever-increasing area.
Fig. 134. - Common Bond.
Common Bond. - A brick laid with its side parallel to the face of the wall is called a stretcher; when laid at right angles to the wall, so that its end is parallel to the face of the wall, it is called a header. Common brick walls in this country are almost universally built by laying the brick all stretchers for from four to six courses and then laying a course of headers as shown in Fig. 134. When the wall is more than one brick in thickness the heading courses should be arranged either as at A or B, Fig. 135. For first-class work the wall should be bonded with a heading course every sixth course.
Fig. 136. - Plumb Bond.
244. Plumb or diagonal bond (sometimes called American bond) is generally used when the wall is faced with pressed brick. The face brick are laid all stretchers with the joints plumb above each other from bottom to top of the wall, as shown at A, Fig. 136. The bonding of the face brick to the common brick is accomplished by clipping off the back corners of the face brick in every sixth or seventh course and laying diagonal headers behind, as shown at B, Fig. 136.
This does not make as strong a tie as a regular header, but if carefully done it appears to answer the purpose. Very often where this bond is used only one corner of each face brick in the outside course is clipped, so that only half as many diagonal brick, or headers, as are indicated in Fig. 136 are used. This of course does not make as strong a bond as when both of the back coiners are clipped. In walls exceeding one story in height the architect should see that both corners are clipped. The strongest method of bonding for face brick is by the Flemish or cross bond, described in Section 245. The objection to these bonds, however, is the increased expense occasioned by using so many face brick headers and also that the face brick and common brick do not usually lay to the same heights, so that it would be necessary to clip the common brick if face brick headers were used in every course, or even every third or fourth course.
Face bricks, when laid as in Fig. 136, are often tied to the backing by pieces of galvanized iron or tin (as shown in Fig. 137), which have their ends turned over a stiff wire about 4 inches long. The wire is not absolutely essential, but should always be used in firstclass work. A still better tie for bonding face brick to the backing-is the Morse Wall Tie, shown in Fig. 138.
This tie is made from 5/32 and 1/8-inch galvanized steel wire 7, 9, 12 and 16 inches in length. The 5/32-inch wire is used for ordinary pressed brickwork, and the 1/8-inch size for very closely laid work. It is now very extensively used in the Eastern portion of the country.
Fig. 139. - English Bond.
Fig. 140. - Flemish Bond.
One advantage obtained in using the metal tie is that it is not necessary that the joints in the face work and backing shall be on the same level, as the ties can be bent to conform to the difference in level, as shown in Fig. 137. Face brick bonded in this way should be tied at least every fourth course with one tie to each face brick.
245. English bond (Fig. 139) is a method of bonding much used in England, and consists of alternate heading and stretching courses.
It is probably the strongest method of bonding common brick, but it is not applicable where face brick are used. It does not make very attractive work, and is scarcely ever used in this country.
Flemish bond, shown in Fig. 140, consists of alternate headers and stretchers in every course, every header being immediately over the centre of a stretcher in the course below; closers (a) are inserted in alternate courses next to the corner headers to give the lap. This makes a very strong bond, but cannot be used with face brick unless the common brick are a little smaller than the face brick, so as to lay up even courses. A modification of this bond, consisting of laying every fifth course of alternate headers and stretchers, is sometimes adopted. It makes stronger work than the diagonal bond and looks about as well.
English cross bond is a variety of English bond said to be much used in Holland, its name being suggested by the appearance of the surface, on which the bricks seem to arrange themselves into St. Andrew's crosses. It only differs from ordinary English bond in that the stretchers of the successive stretching courses break joint with each other on the face of the wall, as well as with the headers in the adjoining courses, as shown in Fig. 141. This makes a much better looking wall than the ordinary English bond.