Heading Bond consists entirely of headers. As bricks vary in length more than in any other dimension, their ends project unequally on the face, and it is difficult, therefore, to make neat work with this bond, especially in walls one brick in thickness. There is very little longitudinal strength in the wall, and the pressure on each brick is distributed over a comparatively small area (see Fig. 23 compared with Fig. 1).
Heading bond is chiefly useful in working round sharp curves, where the angles of stretchers would, unless cut off, project too much, and spoil the curve. When used in this position, the sides of the bricks must be roughly cut, so as to radiate from the centre of the curve, or a curve may be gained, when it is not too sharp, by making the joints of wedge shape wider on the outer face of the curve.
In walls of heading bond more than one brick thick, a line of bats or half-bricks must be introduced, in alternate courses, to form the transverse bond.
Stretching Bond consists entirely of stretchers, and is adapted only for walls 1/2 brick thick.
In walls beyond that thickness (see Fig. 1) it is practically no bond at all. There is no transverse tie. The block is divided into a number of independent 4 1/2-inch walls.
Stretching bond is, however, commonly used in chimneys when their external walls are only 4 1/2 inches thick, and has, in conse-cpience, received the name of "chimney bond."
English Bond shows both on face and back, stretching and heading courses alternately, closers being inserted as shown, and as before described, to give the lap (see Fig. 24).
This is the best bond for work generally. It gives the most simple combination for longitudinal and transverse strength.
Fig. 23. Heading Bond.
Fig. 24. English Bond.
In the last-mentioned wall each course contains a row of headers and one of stretchers, the headers and stretchers appearing alternately on opposite sides of the wall.
This latter will be found to be the case in every wall whose thickness is an uneven number of half bricks. In such, every course showing stretchers on the face will show headers at the back, and vice versa. See Figs. 35, 36, and others.
In a wall whose thickness is a multiple of a whole brick, that is, of 9 inches, every course will show the same both on the front and back of the wall - that is, either stretchers on both sides, or headers on both sides, in the same course.
Figs. 25, 26, 27. English Bond, 9-inch wall.
Figs. 28, 29, 30. English Bond, 14-inch wall.
In walls more than 14 inches thick, though the external rows of bricks are headers or stretchers in the alternate courses; yet those within the wall are all laid as headers. Stretchers within the wall would cause straight joints.
The bricks should not break joint with each other in the same course. The transverse joints should be straight, as shown.1 Any attempt to break these joints, though it may look better in the plan of each course, leads to a large number of vertical joints being brought together in the body of the work (see pp. 20 and 26).
1 See p. 20.
Figs. 37, 38, 39. English Bond, 2' 3"-wall.
Figs. 34, 35, 36. English Bond, 1' 10 1/2"-wall.
Figs. 31, 32, 33. English Bond, 18-inch watt.
Figs. 31 to 39 give plans of the courses, showing the junction at angles, and sections of walls from 2 to 3 bricks thick.
It will be seen that in walls more than 14 inches thick there is a deficiency of stretchers in the centre of the wall. This can best be remedied by introducing courses of bricks placed diagonally, the bond for which will be explained in Part II.
The number of stretchers is less in proportion as the wall grows thicker, being as follows: -
In a l 1/2-brick wall the number of stretchers is 1/2 that of the headers.
In English bond there are twice as many vertical joints in a heading course as there are in a stretching course; therefore the vertical joints between the headers must be made thinner than those between the stretchers; for if two headers were laid so as to occupy a greater length than one stretcher, the 1/4-brick lap obtained by the aid of the closer would be encroached upon, and would soon disappear.
The figures given above show the bond used for walls meeting at the ends to form a right angle, which is the most common case in practice.
If, however, a wall is detached and terminated only by its ends being cut off square, as shown in Figs. 40 to 43, the bond has to be slightly modified, so as to give the ends a neat finish.
Figs. 40, 41. English Bond, detached 14-inch wall.
Figs. 42, 43. English Bond, detached 18"-wall.
In such walls, when they are of an uneven number of half bricks in thickness, a peculiarity must be noticed - both sides do not present the same appearance. The closers show both in the stretching and heading courses alternately; but in walls whose length is equal to that of an even number of half bricks, a bat must be introduced among the stretchers on the face in which the closers occur in the stretching courses, whilst in walls whose length is equal to that of an uneven number of half bricks, the bats will show in the stretching courses which do not contain the closers; the face with the bats should form the back of the wall.
Fig. 41 shows an example of this; the bat referred to being at b.
Figs. 42, 43 give plans of two courses of an 18-inch wall, with returned ends. Want of space forbids any further illustration of such walls; but the student should draw them for himself, bearing in mind what is stated above, and remembering also that the returned ends of thick walls should be treated so as to show a bond similar to that on the faces of the walls.