This section is from the book "Modern Buildings, Their Planning, Construction And Equipment Vol1", by G. A. T. Middleton. Also available from Amazon: Modern Buildings.
The appearance of double Flemish bond is shown in Fig. 121, in which it will be seen that in each course headers and stretchers alternate, the face of the headers coming centrally above the faces of the stretchers in the course below. As in English bond, the lap is produced by placing a queen-closer next to the quoin-header in every course. This system of bonding is much weaker than English bond, on account of the large proportion of vertical joints - blackened in Figs. 122, and, in the case of walls of an odd number of half-bricks in thickness, of the small proportion of headers generally used in their interiors. The advantages of Flemish bond are, that it is economical when expensive facing bricks are used, as it only requires 64 headers per square yard when all are whole bricks, against 72 per square yard required for English bond; that walls one brick in thickness are easier to produce a fair face on both sides in Flemish than in English bond; and that, in the opinion of many, the appearance of Flemish bond is preferable to that of English bond.
Besides the general rules given on page 66, there are several others which apply particularly to double Flemish bond: -
1. There should always be a quoin-header in every other course.
2. There should always be a queen-closer next to the quoin-header, which is broken at 1-brick intervals through the whole thickness of the wall.
3. Each course should consist of headers and stretchers alternately.
4. Except in 3-half-brick walls, the headers and stretchers on one face of the wall should be respectively opposite headers and stretchers on the other face of the wall in the same course.
Fig. 122. - Double Flemish Bond.
It will be noticed that in walls of an odd number of bricks in thickness a considerable number of half-.bats occur, while the proportion of headers in the interior of the walls is small; and in the case of walls of 5, 7, ect. half-bricks thick the proportion of continuous vertical joints is double that occurring in walls of an even number of half-bricks in thickness. In spite of this defect, 2 1/2-brick walls are usually built as in Fig. 122, unless specified otherwise, on account of the economy in facing bricks, only 56 per square yard being required, as two of the half-bats or false headers are formed by cutting one facing brick in half. The remedy for this defect is to make the bricks B,B,B (see Fig. 122) three-quarter bats, as well as those immediately behind them.
Single Flemish Bond is a species of bond in which the face of the walls shows alternate headers and stretchers in each course as in double Flemish bond, while the rest of the wall is built in English bond. It is used when the appearance of the former and the strength of the latter are required.
FlG. 123. - Single Flemish Bond.
In building walls in this bond the external facings are first laid as in Flemish bond and the internal facings are laid as in the bonding diagram in Fig. 84, while the interior of the wall is filled in with as many headers as possible. Alternate courses of walls from 1 1/2 to 3 bricks thick are shown in Fig. 123. It will be seen that this system cannot be employed in walls of less than 1 1/2 bricks thick.
The stopped ends may be formed as in English or double Flemish bond, but it is customary to employ the former.
When expensive facing bricks are used, the bricks B,B,B (Fig. 123) are frequently made false headers for the reasons already explained, but where maximum strength is required they should be made whole or three-quarter brick as the exigencies of the case require, and the sizes of the adjacent bricks are altered accordingly.
Plain Jambs are bonded in precisely the same manner as stopped ends, those in double Flemish bond being shown in Figs. 122, while those in single Flemish bond are shown in Fig. 123, and it will be noted that in the latter case the system is the same as that employed in English bond.
The method of forming 2 1/4-inch reveals in double Flemish bond is shown in Fig. 124.
Examples of rebated jambs in double Flemish bond with 4 1/2-inch reveals are shown in Figs. 125 and 126, and those with 9-inch reveals are shown in Fig. 127.