The primary materials used to create bricks are clay, concrete, and calcium silicate. The materials are known for their mechanical properties. They offer several advantages like strength, density including improved insulation, plastering support as well as reduced cost. Some bricks are designed specifically for plastering.

Clay Bricks

When selecting the right kind of brick for the job, it is good to consider a number of important factors such as fire resistance, moisture movement and thermal movement. In addition, it is also good to put into consideration other things like thermal characteristics, pore structure and weight. Furthermore, it is good to check out a brick’s density, surface texture and colour before buying.

Raw materials

Fired clay bricks are made from naturally occurring clays and shales. In most instances, the choice of a particular clay and/or shale will be the major factor in determining the colour of the final product. Quite a few brick types are made from clay only and contain no shale. Some brick colours and textures are achieved through the addition of other minerals to the base clay.


Extruded bricks bricks (with holes in them) are made by forcing a continuous column of clay through a mould and cutting the column into individual bricks one section at a time with a series of wires. The holes in extruded bricks are created by the design of the mould and allow mortar to lock the bricks together when they are laid.

Pressed bricks are made individually in mould boxes. Instead of having holes through them, bonding with the mortar in the finished wall is achieved by the frog, the name given to the indentation in the top of a pressed brick.

Australian Brick Manufacturers

Here are links to particular Australian Brick Manufacturers.

Austral Bricks

Bendigo Brick Pty Ltd

Boral Bricks

Bowral Brickworks (Austral)

 Hallett Brick (Austral)

 Littlehampton Brick Co. (Austral)

Metro Brick (Austral)  

Midland Brick (a division of Boral)

Namoi Valley Brickworks





The dimensions of a brick vary depending on the place of manufacture. For instance, a standard brick in Australia at present there are Australian Standards which are met fairly consistently across the country. A standard metric brick is 230 x 110 x 76mm high, and a metric modular brick is 90 x 290 x 90 high. Seven courses of a standard brick (76+10=86 mm) would make up a height of 602mm, but the bed joints are adjusted so that seven courses come to a module of 600mm. A modular metric brick and its joints occupies 300 x 100 mm on the face, so that modular dimensions of 100 and 300mm are easily met.

To increase productivity, a range of bricks are available with a larger face size. In most cases they retain the standard 230 length, but vary in width and height. Most of these are not intended to be used for facework, but can be used for both internal and external walls that are intended to be rendered and painted.

Typical sizes of Australian bricks are:

  • 230 x 150 x 76 (thick for party wall)
  • 230 x 110 x 119 (one-and-a-half course height)
  • 230 x 150 x 119 (thick, one-and-a-half course height)
  • 230 x 90 x 162 (thinner, two-course height)
  • 290 x 90 x 162 (two-course height face blocks, made in Western Australia)
  • 290 x 90 x 119 (one-and-a-half course height face blocks, made in Western Australia).

Size tolerance

Because of the manufacturing process, bricks can be expected to vary in size a little. A small variation between individual bricks can easily be accommodated in the joint thickness.

The standard AS/NZS 4455-1997 defines the average size by measuring a set of 20 bricks together, and individual variations by sampling individual bricks.


Bricks undergo shrinkage as the initial drying process drives off free water from the green brick, and during kiln firing. Manufacturers generally test fire each new clay deposit coming into production, to ensure that the end product complies with the dimensional tolerance of +/- 60 mm in 20 bricks for category DW2.

Autoclaved  Aerated Concrete (AAC)

Autoclaved Aerated Concrete (often shortened to ‘AAC’) is effectively concrete with lots of closed air pockets in it. It is lightweight and energy efficient, and is produced by adding a foaming agent to concrete in a mould, then wire cutting blocks or panels from the resulting ‘cake’, and ‘cooking’ it with steam (autoclaving).

The use of AAC in Australia is not yet widespread but autoclaved aerated concrete blocks have been used in Europe for more than 50 years.

AAC blocks are laid in much the same way as bricks but using adhesive to form a monolithic structure. Typically, external walls use a single skin of 250mm thick blocks while internal, non-load bearing walls use 100mm thick blocks.

Walls built with AAC-Blocks are strong and durable, providing the security of solid masonry with the added advantages that the unique nature of AAC can deliver.

Compared to traditional double brick construction, AAC-Block walls can be laid much faster, saving time and building costs

Table 2.1: Product Range for CSR Hebel Blocks, Lintels & Stair Treads





Stair Tread



Nominal AAC Dry Density







1200, 1900, 2200, 3000, 6000

1000, 1200





300, 400, 600




75 - 300

100, 150, 200



Notes:  *Thicknesses are available in 25mm increments.

Here are links to particular Australian AAC Manufacturers.

CSR Hebel

Autoclaved Aerated Concrete (AAC), an amazingly innovative building material.

One Stop Building and Hardware

Suppliers of Autoclaved Aerated Concrete (AAC) panels, Ecol-One, and Ecol-Mega range of panels. Warranty of 7 years is available on panel products. More...


Concrete blocks

Most concrete masonry units used in Australia are manufactured by automatic machinery. Concrete masonry blends fine sand, cement, aggregate and, for coloured blocks, quality colouring agents. Grey concrete blocks are the construction industry’s ‘workhorse,’ a tribute to their strength and versatility.

Concrete masonry units, for use in walls, fall into two broad categories

  1. concrete bricks and
  2. hollow concrete blocks.

 Other concrete units such as concrete segmental pavers, retaining-wall blocks and landscaping units are also produced.


Click on the link for information.


Concrete blocks are usually:

  • 90, 119, 162 or 190 mm high
  • 90, 190, 290 or 390 mm long
  • 90, 110, 140, 190 or 290 mm wide, (100, 120, 150, 200, 300 Series)

The longer units usually have two (sometimes one, sometimes three) cores extending vertically through the block. Many other shapes known as ‘fittings’ and ‘fractions’ are produced for corners, openings, sills, bond beams, retaining walls and landscaping applications.

Concrete blocks often used for reinforced concrete block walls with steel bars placed vertically and horizontally, and all cores in the blocks are filled with semi-fluid concrete, known as ‘grout’.

Earthwall construction

Mud brick (Adobe)

Basic mud bricks are made by mixing earth with water, placing the mixture into moulds and drying the bricks in the open air. Straw or other fibres that are strong in tension are often added to the bricks to help reduce cracking. Mud bricks are joined with a mud mortar and can be used to build walls, vaults and domes.

Structural capability

With thick enough walls, mud brick can create load bearing structures up to several stories high. Vaults and domes enable adobe to be used for many situations other than vertical walls. The mud brick may be used as infill in a timber frame building or for load-bearing walls, although its compressive strength is relatively low. Typically, Australian adobe structures are single or double storey.

Rammed earth (Pise)

Rammed earth is a method of building walls whereby a mixture of earth is compacted in layers between forms. Each layer of earth is approximately 15 cm (6 inches) deep. As each form is filled, another form is placed above it, and the process begins again. This is continued until the desired wall height is achieved. Forms can be stripped off as soon as the form above is begun, as the compressed earth wall is self-supporting immediately. Most rammed earth use pneumatic rammers to compact the earth within the forms.

The external walls of our rammed earth buildings are a minimum of 300mm (1 ft) thick, providing excellent protection from extremes in climate. The thickness and density of the material means that heat (or cold) penetration of the wall is very slow and the internal temperature of the building remains relatively stable, with the end result of it feeling warmer in winter and cooler in summer than the outside temperature

Structural capability

Rammed earth is very strong in compression and can be used for multi-storey load-bearing construction. Research in New Zealand indicates that monolithic earth walls perform better under earthquake conditions than walls made of separate bricks or blocks. There is a five storey hotel in Queensland built of stabilised rammed earth. Rammed earth can be engineered to achieve reasonably high strengths and be reinforced in a similar manner to concrete, although horizontal reinforcement is not recommended and excessive vertical reinforcement can cause cracking problems.

The FORMBLOCK Wall Building Kit is an easy to assemble modular system of in-situ block making formwork, suitable for stabilized earth, or concrete.

Natural stones

An understanding of natural stone’s basic properties is important for the selection of an appropriate stone for a project. This link provides you with all necessary information about natural stones.

Natural stones are used in construction projects ranging from retaining walls, residential homes, commercial buildings and landscapes. An important economic factor for using natural stones can be the high cost of transportation.

© Karl Boeing