Pitman's Vol 4 - Bonding

Front Cover of Volume 4

Building Educator
Volume 4

by R Greenhalgh (Ed)

Published by Pitman & Sons Ltd
27th November 1926

No ISBN number

General Principles of Bonding
The arrangement of bricks when building, is of great importance, as upon this depends the strength and appearance of the work

Wall without Bond
Fig. 7 - Volume 4, page 157

Consider Fig.7, it is clear that a wall built in this manner would tend to split along the continuous vertical joints,
if subjected to any irregular strain

The section A, B and C are entirely independent and receive no support from each other

If, however, the wall is built in the manner of Fig. 8, the whole mass is in combination and mutually supported

Bonded Wall
Fig. 8 - Volume 4, page 157

The same quantities of materials have been used and the same labour expended in each case, but there is no comparison between the strengths of the two examples

In Fig. 8 it will be noticed that the bricks in one course overlap those in the course below, forming an interlocking arrangement throughout the whole wall

This arrangement is called Bonding

There are several recognized types of bond, the two main ones being English and Flemish. If the principles of these two are thoroughly understood, the others, which are but variations of them, will present no difficulty

Rules for Good Bonding

1. The amount by which the bricks in one course
   overlap the bricks in the course below should be:
   
   ¼-brick along the length of the wall and
   ½-brick through the thickness of the wall
   
    
2. The vertical joints in the alternate courses should fall in a plumb line from the top of the wall to its base, whether on the face or in the interior of the wall
   
    
3. Bats should be used as little as possible, and where used, should be evenly distributed throughout the whole of the work
   
    
4. The bricks should be uniform in size, and the proportion of length to breadth be such that the length equals twice the width plus one joint
   
   Good bond is impossible otherwise, as the lap
   would not be uniform
   
    
5. The bricks in the interior thickness of the wall
   should be laid with their length across the wall,
   or as it is termed, headerwise

Flemish Bond
The facing bricks in this bond are laid as alternate headers and stretchers in the same course

It is not as strong as English bond, on account of the numerous straight joints, which occur repeatedly throughout the wall, and the greater number of bats that are used, particularly when the wall has an odd half-brick in its thickness

If the bond is carefully arranged, it is considered sufficiently well bonded for all general purposes

Careless workmanship in this respect has, however, been the cause of walls built in this bond splitting in two along their thickness

English Bond
In this bond the facing bricks are laid in alternate courses of headers and stretchers. This is undoubtedly the strongest of all bonds; the arrangement of the bricks is such that no joint or part of a joint is continuous with any joint in the course below, or, as it is often stated, there are no straight joints

Method of Bonding
Fig. 9 is an isometric view of English Bond,
at the external corner, or quoin of a building

Note that the bond on the external faces change in the same course - at A, they are stretchers; at B, headers

One-Brick Wall in English Bond
Fig. 9 - Volume 5, page 158

Observe also, that the first header on the quoin is followed by a small bat, ¼-length of a brick. This is termed a closer, and its object is the commencement
of the bond

It will readily be seen that the insertion of the closer moves the second header ¼-brick along the wall, which
is the necessary distance for the lap over the stretcher below. This is repeated throughout the length of the wall

Also notice, that all joints crossing the thickness of the wall pass from the exterior face to the interior in a continuous line

We have now three definite facts to memorize;

1. Where a wall changes direction, the face bond
   in the same course changes
   
    
2. That the quoin header is followed by a closer, although there are exceptions to this rule,
   which will be explained later
   
    
3. That all transverse joints should pass in an uninterrupted line across the wall

One-and-Half Brick Wall in English Bond
Fig. 10 - Volume 5, page 158

Fig. 10 shows a portion of a 1½-brick wall at the quoin
of a building. Here, it is noticeable that the bonds on
the exterior and interior faces of the same course are different, whereas those shown in Fig. 9 depicts headers on both faces

Also, the heavily outlined bricks in the interior angles, called tie-bricks, are in different positions. The tie- brick in Fig. 9 has its header face parallel with the wall face, whilst in Fig. 10 the stretcher face is in that position. But in both cases, ¼ of this tie-brick bonds into the return corner

From the foregoing we may deduce some more facts;

4. That where a wall has an even number of half-bricks in its thickness, the bond on the interior and exterior faces of the same course is the same, and that the tie brick in the interior angle has its header face parallel with the wall
   
    
5. That where a wall has an odd number of half-bricks in its thickness, the bond on exterior and interior faces of the same course is different, and the tie-brick has its stretcher face parallel with the wall face

Fig. 13 shows part of one course of a 2-brick wall

The bond is the same on both faces; bricks in the interior of the wall are laid headerwise, and the unit repeats itself on either face

Two-brick wall
Fig. 13 - Volume 4, page 159

Fig. 14 indicates a 2½-brick wall. The unit repeats itself along one face only, its thickness being insufficient to take two units.

2½-brick thick English Bond
Fig. 14 - Volume 4, page 159

The interior bricks are laid headerwise, and transverse joints cross the wall in a straight line, unless stopped
by a face stretcher. As the wall has an odd half-brick in
its thickness, the bond on its opposite faces is different.

In Flemish bond, let us consider the unit to be a face header and stretcher. In a 1-brick wall, Fig. 15, this repeats on both faces.

1-brick thick Flemish Bond
Fig. 15 - Volume 4, page 159

In a 1½-brick wall, Fig. 16, the headers are laid side by side on the opposite faces of the same course

1-brick thick Flemish Bond
Fig. 16 - Volume 4, page 160

In 2-brick wall, Fig. 17, the headers are arranged to be opposite each other in the same course

2-brick wall in Flemish Bond
Fig. 17 - Volume 4, page 160

Now remember some of the previous rules:

The bricks in the interior thickness of the wall should be laid headerwise; bats are to be used as little as possible, and distributed evenly in the interior thickness.

It will be seen in the arrangements shown, that in the one and two-brick walls, no bats are required. In the 1½-brick wall, a certain number unavoidable

Two different methods of arranging the bricks in one course of a 2½-brick wall are shown below

Inferior method of bonding
Fig. 18 - Volume 4, page 160

Where the face-headers are opposite each other, Fig. 18, a large number of bats is required. When these headers pass, as in Fig. 19, the number of bats is considerably less, and they are more uniformly distributed.

Good method of bonding
Fig. 19 - Volume 4, page 160

In Flemish bond, therefore, it can be assumed that where a wall has an odd half-brick in its thickness, the facing headers should be arranged so they pass each other

If an even number of half-bricks in thickness, the face-headers should be arranged opposite each other

These arrangements will usually be found to provide a more uniform bond, involving the use of the least possible number of bats, and, in consequence, producing a much stronger wall.

Note that in Flemish bond, the face-headers are always placed over the centre of the stretcher in the course below, and never over a perpend.

Single Flemish Bond
Fig. 20 - Volume 4, page 160

Flemish bond is frequently used as a facing bond only, the remainder of the wall being built in English bond. To put it concisely, Flemish facing with English backing, and this is usually termed single Flemish bond.

The object is to obtain the greatest strength possible, where Flemish facing is desired. In this type of bonding, the facing headers in alternate courses are half-bats, or, as they are termed, cropped headers, see Fig 20.