Bricks are laid to expose their ends (Header bricks), or sides (Stretcher bricks). As the work progresses, the bricks are laid in rows called courses. The manner in which the bricks overlap as they are laid up is called the bond of which there are two main types: half bond and quarter bond. Types of bonding arrangements include English bond, Flemish bond, and Herringbone bond, but the most common type of brickwork seen these days is the simple stretcher bond, showing only the long side-surface of the brick.
Because only the outside of finished brickwork is visible, cheaper grades of brick are commonly used for the hidden parts of a wall. In an old red-brick house, behind the front of red, the rest of the walls are often made of softer yellow bricks. The colour situation may be reversed if the house was built when red bricks were out of fashion. So with certain types of bond (e.g. garden wall bond) it is possible to use a higher ratio of cheaper bricks to more expensive bricks, making for a cheaper wall of the same dimensions. On the same house, sometimes a more economical "garden wall" bond has been used at the side and rear compared to the front.
The thickness of brickwork is casually quantified in units of brick referring to the length of a brick. A double-skinned wall will have some bricks laid across both skins or courses and therefore the wall will be as thick as the length of the brick. Because most typical bricks are roughly twice as long as the are wide, a single-skinned (or single course) wall with bricks laid end to end will be as thick as the brick as wide, which is roughly half the length of a the brick it is called "half brick" thick. Simply put, single-skinned walls are expediently or casually referred to as "half brick" thick and double-skinned walls "full brick" thick even though technically this is only an approximation relevant to bricks roughly half as wide as they are long.
If bricks are put down end-to-end with the long side facing you (stretchers) and then another row on top, the wall thickness is half a brick.
There are rules of bonding, which have some exceptions. These specify the overlap between courses that is visible outside the wall, and also the overlap which must be made within the wall, for walls which are more than half a brick thick.
Brickwork, like unreinforced concrete, has little tensile strength, and works by everything being kept in compression.
The thickness of a brick wall is measured using a unit of length known as 'the brick'. This standard can be used consistently with the wide variety of brick sizes available ("modular, "Norman" brick, etc.). The length of the longest face for a particular size of brick equals "one brick", for the purposes of measuring a wall built from such bricks.
Stretcher bond (also known as running bond) is the most common bond in modern times, as it is easy to lay, with little waste. It is entirely composed of stretcher bricks, set in rows (or "courses") that are offset by half a brick.
Running bond uses no header bricks, allowing for a thin wall of one layer (half of a 'brick' unit). Two such walls may be built close together with a gap between. The two "skins" are usually tied together at regular intervals using wall ties. For this reason this bond is sometimes known as "cavity wall bond", although it is possible to give the appearance of other bonds in a half-brick cavity wall, either through extensive brick-cutting or the use of purpose-made half-bricks. In some climates the cavity may be filled with cavity wall insulation.
Stretcher bond may also be used to build a single-wythe (one-brick thick) wall without a deliberate cavity. In this case, wall ties are used to hold the two wythes together. The main advantage of this technique is that it allows walls with both faces visible, such as domestic dwarf walls (low-height walls where the part of the structure above is built of a lighter, framed material such as glass) to be built using low-cost bricks that have only two fair faces, called "face bricks". Laying any such brick as a header would reveal a poorly finished header face on one side of the wall. These walls are also used in situations where stronger load-bearing capacity is required than that given by a single stretcher bond wall with engaged piers.
This bond is made up of alternating courses of stretchers and headers. This produces a solid wall that is a full brick in depth. English bond is fairly easy to lay and is the strongest bond for a one-brick-thick wall. If only one face of an English bond wall is exposed, one quarter of the bricks are not visible, and hence may be of low visual quality.
Header bond (also known as Spanish bond) was a very common bond for bearing walls. It is composed of header bricks, set in rows that are offset half a brick, which produces a solid easy to lay bond which is useful when building circular work. It is the most used bond in historical Spanish brick constructions. Picture shows stretcher bond.
A common variation often found in early 18th century buildings is Glazed-headed Flemish Bond, in which the exposed headers are burned until they vitrify with a black glassy surface.
Monk bond is a variant of Flemish bond, with two stretchers between the headers in each row, and the headers centred over the join between the two stretchers in the row below.
These bonds are variations on normal bonds. They use a high proportion of stretchers, and hence require fewer facing bricks than normal bonds. This makes them less sturdy, but cheaper to lay. As such they are most commonly used for garden- and other non-load-bearing walls.
Rat-trap bond, also known as Chinese bond, is a type of garden wall bond in which the stretchers and headers are laid on their sides, with the base of the stretcher facing outwards. This gives a wall with an internal cavity bridged by the headers, hence the name. The main advantage of this bond is economy in use of bricks, giving a wall of one brick thickness with fewer bricks than a solid bond. Rat-trap bond was in common usage in England for building houses of fewer than 3 stories up to the turn of the 20th century and is today still used in India as an economical bond, as well for the insulation properties offered by the air cavity. Also, many brick walls surrounding kitchen gardens were designed with cavities so hot air could circulate in the winter, warming fruit trees or other produce spread against the walls, causing them to bloom earlier and forcing early fruit production.
When bricks are laid on alternating angles, it is called a Herringbone. This is primarily a decorative style, more often used for paving or fireplace reflectors than for walls. It is generally considered unsuitable for load-bearing structures, but may be found as infill in traditional timber framed buildings. This style is also sometimes called by its Latin name: Opus spicatum.
This decorative pattern imitates the weave of a basket. It's also sometimes called a basket weave bond, and there are many variations on the weave pattern, some very elaborate.