In his first article on brick bonds, Mike Hammett discusses the characteristics of basic configurations
When the vertical joints between bricks in the face of the brickwork do not align in adjacent courses, this known as “bonding”. Bonded brickwork dimensioned and built to a regularised system creates a neat appearance and minimises the need to cut bricks; it also promotes the even distribution of forces applied to the brickwork by floors, beams, roofs, and so on.
When bricks are not consistent in size, as in some early medieval brickwork, they are overlapped, but not in a regular pattern. This arrangement is described as haphazard bonding. Bricks of reasonably consistent dimensions can be laid in regular bonding arrangements that create distinctive patterns of stretchers and headers in the face of brickwork. There are a number of configurations, but most are variations within three basic arrangements – English bond, Flemish bond and stretcher bond.
English and Flemish bonds are used in brickwork of one brick (215 mm) or thicker. Some of the bricks are placed with their stretchers (long faces) parallel to the surface of the work; the others are placed at right angles so that their headers (ends) appear in the surface of the work and they lap over and bond with bricks behind the surface. English and Flemish bonds are said to be quarter bonded because the overlap is half the width of a header, equivalent to a quarter of the length of a brick.
Courses of stretchers alternate with courses of headers in English bond. It is the oldest pattern and in some countries is known as ancient bond. It is regarded as the strongest bonding arrangement possible as there are no continuous vertical joints within the thickness of the brickwork.
The visual contrast between courses of headers and courses of stretchers tends to emphasise horizontality. Differences of colour or tone between headers and stretchers can produce a pronounced stripy appearance. English bond and its variations were used for all types of brickwork until the introduction of Flemish bond in the mid 17th century.
Variations in setting out create subtle cross and diagonal motifs in the work. Introduction of additional headers, some of contrasting colour, creates the decorative diaper patterns characteristic of 16th-century Tudor brickwork.
In Flemish bond, stretchers and headers alternate in each course. There is no directional emphasis in the surface pattern, which is regarded as having a more refined appearance than English bond. Its superior appearance won great favour in the Georgian period and it has been widely used ever since. However, its internal bonding arrangement produces continuous, narrow, vertical joints parallel to the wall surface. In theory, this weakens the bond and is why English bond continued to be preferred for civil engineering work and industrial buildings.
Economic expediency and variety of pattern
Where a small a reduction of strength is acceptable, for example in freestanding walls or buildings of domestic scale, the basic bond patterns are often varied to show a greater proportion of stretchers in the face of the wall. This reduces the number of bricks in the face and consequently the cost of thick walling because the majority of bricks are internal, not subject to weathering and so can be of lesser quality. Such variants are often referred to as “garden wall” bonds, but they are frequently used in buildings.
English garden wall bond has courses of headers with three courses of half-lapped stretchers between them. Incidentally, Scotch bond is a variant with five courses of stretchers and American bond has seven. Flemish garden wall bond has three stretchers between single headers in each course and is also known as Sussex bond.
Stretcher bond, or stretching bond, is extensively used in modern building, primarily in cavity walling. The bricks are laid end to end in courses with the stretchers showing in the face of the work. Each brick laps over two in the course below.
For simplicity, stretcher bond is normally built with bricks overlapping by half their length. Variations in which the overlap is a third or a quarter of the brick length produce an attractive diagonal inflection. However, they are not common, probably because they require greater care in laying in addition to special cutting at corners and ends.
One-brick-thick walls that are required to be fair-faced on both sides are often built as two stretcher bonded “leaves”. This arrangement is called a collar-jointed wall with the leaves fixed together by flat stainless steel ties that are laid at the same frequency as ties in a cavity wall. Alternatively, welded stainless steel wire, ladder-pattern reinforcement built in across the wall in every third or forth bed joint is convenient for straight work.
English and Flemish bonds with cavity walling
English or Flemish bonds can be replicated in the half-brick outer leaf of a cavity wall by using whole bricks as stretchers, while the headers are created by half bricks called bats or snap-headers. This technique is not a modern conceit; textbooks contemporary with early cavity wall construction anticipated the practice as normal. The bats should be cut carefully, preferably using a masonry power saw.
Either half-stretcher faces or true headers can be used in the face of the work. The obvious option is to use the headers, but sometimes they are a slightly different colour and so half stretchers might be a better choice. Also half stretchers will be slightly wider than headers and so will necessitate narrower vertical joints between the bricks – a common feature of older brickwork. Whatever the choice, be consistent to avoid a patchy appearance.
In header bond, or heading bond, only the ends of bricks show in the face of the work. It has a fine, very ordered, appearance. Historically it was used for buildings of high quality, often using bricks with grey or black coloured ends.
Header bond cannot cope with corners and for this reason the quoins and jambs of openings in header bonded walling are often formed of normally bonded brickwork in a contrasting colour.
Curved brickwork is often built in header bond, because the extra joints and short faces produce a smoother curve.
In stack bond the bricks do not overlap and therefore the arrangement is inherently weak. To compensate for the lack of bonding, typically stainless steel ladder reinforcement is built into every third bed-joint.
Placing normal wall ties in the same joints as the reinforcement should be avoided, as the resulting bedding joint tends to become thick and unsightly. However, this may be unavoidable where stack bonded soldier courses are concerned. The use of oval or flat sectioned stainless steel wire reinforcement and thin stainless steel sheet wall ties would be an advantage.
To look good, straight vertical joints are essential and the bricks may require selection to ensure acceptable consistency of size.
Setting out and broken bond
Ideally brickwork dimensions should be in increments of brick length. The bond pattern will then work out without cutting bricks (other than closers or three quarter bats used at corners and ends). If non-incremental dimensions are unavoidable, then cut bricks will be used to adjust the pattern – this is called “broken bond” and good bricklaying practice calls for care in setting it out. Space here does not permit coverage of the various conventions that apply, but for full details of setting out bonding, see Brickwork for Apprentices (4th edition, 1993) JC Hodge & RJ Baldwin [ISBN 0-340-55641-2]
Brick Bulletin January 2005
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