Brick

[edit] Introduction

Bricks are small rectangular blocks that can be used to form parts of buildings, typically walls. The use of bricks dates back to before 7,000 BC, when the earliest bricks were formed from hand-moulded mud and dried in the sun. During the Industrial Revolution, mass-produced bricks became a common alternative to stone, which could be more expensive, less predictable and more difficult to handle.

Bricks are still in common use today for the construction of walls and paving and for more complex features such as columns, arches, fireplaces and chimneys. They remain popular because they are relatively small and easy to handle, can be extremely strong in compression, are durable and low maintenance, they can be built up into complex shapes and can be visually attractive.

However, more recently, other materials have been developed that can be used as alternatives for building walls or for cladding facades and for some building types, particularly larger buildings, bricks can be seen as time consuming, expensive (although this is disputed by the Brick Development Association), structurally limiting, and requiring too much on-site labour. Some of these difficulties have been overcome by the introduction of reinforcement systems and by the development of pre-fabricated brick panels.

For information on bricklaying, see How to lay bricks.

[edit] Size

In the UK, standard bricks are 215 mm long × 102.5 mm wide × 65 mm high.

This gives a ratio of 3:2:1:

• With a standard mortar joint of 10 mm, a repeating unit of bricks laid in a stretcher bond will be 225 mm lengthwise and 75 mm in height.
• If bricks are laid cross-wise, two 102.5 mm widths plus two mortar joints gives the same repeating unit as the length of one brick, ie 225 mm.
• If they are laid height wise, three 65 mm heights plus three mortar joints gives the same repeating unit as the length of one brick, ie 225 mm.

[edit] Manufacture

Bricks are most typically made from clay, although they are also commonly made from calcium-silicate and concrete.

Soft mud or dry-press bricks are formed by pressing the brick mixture into moulds and then firing them in a kiln. Soft-mud bricks are made from a thin mix whereas dry-press bricks are made from a thicker mix that gives crisper definition. Greater strength is achieved by using greater force when pressing the brick and by firing it for longer, but this increases the cost.

Extruded bricks are formed by pushing the brick mixture through a die to create an extrusion that is then wire cut to produce bricks of the required length.

Bricks can be solid, or can have holes perforated through them to reduce the amount of material used. Alternatively they may have an indentation on one surface (or two surfaces) commonly called a ‘frog’. The frog must be filled with mortar when bricks are laid otherwise the structural and acoustic performance of the wall will be affected. For this reason it is best practice to lay bricks with the frog facing upwards so that it is easy to fill. Where there are two frogs, the larger frog should face upwards.

For information about how bricks are tested, see Testing bricks.

[edit] Special bricks

Other than the standard rectangular block, a number of special shapes exist for particular circumstances that may be encountered when building with bricks. These include:

• Radial, tapered or arch bricks.
• Angle and cant bricks that form returns and chamfers.
• Bullnose bricks with rounded corners.
• Capping and coping bricks.
• Cill bricks.
• Plinth bricks.
• Brick slips (thin bricks that can be used for cladding).
• Soldier bricks, that form returns for soldier courses.

Bricks can also be cut to size.

Engineering bricks have particularly high strength, low water absorption and good acid resistance. They are generally used for civil engineering applications.

For more information, see Types of bricks.

[edit] Bonds

Bricks can be laid as soldiers (standing upright), stretchers (laid lengthwise along the wall) or headers (laid width wise along the wall).

Bricks are laid with a mortar joint bonding them together. The profile of the mortar joint (pointing) can be varied depending on exposure or to create a specific visual effect. The most common profiles are; flush (rag joint), bucket handle, weather struck, weather struck and cut, and recessed.

The bonding pattern describes the alignment of the bricks. There are a large number of standard bond patterns, including:

• Stretcher bond. This is the most commonly used bond in the UK. Each stretcher (brick laid length-wise) is offset by half a brick relative to the course above and below.
• English bond. Alternating courses of stretchers and ‘headers’ (bricks laid width-wise) are laid with the alternating courses aligned to one another.
• American common bond. Similar to the English bond but with one course of headers for every six stretcher courses.
• English cross bond. Alternating courses of stretchers and headers, but with the alternating stretcher courses offset by half a brick.
• Flemish bond. Alternating stretchers and headers in each course.
• Header bond. Courses of headers offset by half a brick.
• Stack bond. Bricks laid directly on top of one another with joints aligned. This is a fundamentally weak bond and is likely to require reinforcement.
• Garden wall bond. Three courses of stretchers then one course of headers.
• Sussex bond. Three stretchers and one header in each course.

For more information, see Types of brick bonding.

[edit] Find out more

[edit] Related articles on Designing Buildings Wiki

• Adobe.
• Airbrick.
• Aircrete blocks.
• Blockwork.
• Brick strip foundation.
• Brick veneer.
• Cavity tray.
• Cavity wall.
• Clay.
• Damp-proof course.
• Defects in brickwork
• Efflorescence.
• How to lay bricks.
• K-Briq.
• Mortar.
• Perpend.
• Pointing.
• Practical Building Conservation: Earth, Brick and Terracotta.
• Quoin.
• Rendering.
• Spalling.
• Swift brick.
• Terracotta.
• Testing bricks.
• Treating brickwork with sealant or water repellent.
• Types of brick bonding.
• Types of bricks.
• Unfired clay masonry: An introduction to low-impact building materials.
• Wall tie failure.

[edit] External references

• The Brick Development Association.