Brickwork and blockwork

Bricks and blocks are components of durable masonry construction, in which uniformly shaped individual units are laid in courses with mortar as the bed and binding material. They usually consist of high-mass materials with good compressive strength, formed into units that can be lifted and handled by a single worker. Materials used in masonry construction include brick, concrete and stone, or newer materials such as manufactured stone, timbercrete and glass.

Brickwork is usually left exposed for its aesthetic qualities and blockwork is usually rendered, but most bricks and blocks can be used as facing materials or given a render coating.

Types of brickwork and blockwork

Clay and concrete brickwork

Clay brickwork is made from selected clays that are moulded or cut into shape and fired in ovens. The firing transforms the clay into a building component with high compressive strength and excellent weathering qualities, attributes that have been exploited for millennia. Clay brickwork is Australia’s most widely used external wall cladding.

Clay bricks are affordable, readily available, mass-produced, and thoroughly tested modular building components. Their most desirable acoustic and thermal properties derive from their relatively high mass. They require little or no maintenance and possess high durability and loadbearing capacity.

Concrete bricks are the same size and intended for the same uses as clay bricks. They share many of the same attributes of clay bricks but may require more control joints, may stain more easily and their colour may fade over time. They are more porous than clay bricks and must be sealed to prevent water penetration.

Blockwork

Blockwork is construction with concrete or cement blocks that are larger than a standard clay or concrete brick. To make them lighter and easier to work with, they have a hollow core that also improves their insulation capacity. They are available in a variety of densities to suit different applications. Their convenience and cost effectiveness have made them a popular alternative to clay bricks. They require an additional finish for reasons of aesthetics and water resistance. They are often used to build internal partition walls and retaining walls.

Autoclaved aerated concrete (AAC) is used to make a special kind of concrete blockwork much lighter than normal concrete and with significantly higher thermal resistance.

Stonework

The cutting of stone into building blocks is an ancient tradition and the basis of some of the world’s oldest buildings, but it is rarely part of modern construction. In modern Australian housing, stone masonry is typically used for feature walls, fireplaces, garden walls and landscaping. Stone has substantial thermal mass and its use inside the home should be considered carefully to gain maximum performance benefits.

Stone masonry is extremely durable – it has provided some of history’s most enduring monuments – but its moisture resistance varies enormously. Generally, the harder the stone the greater its moisture resistance. Any flaws, porosity or cracking that allow moisture penetration will compromise its overall resistance to weathering, particularly in frost-prone regions.

Stone masonry is widely available. A high proportion of stone is imported into Australia, including specialist marbles from Italy and cheap slate from India. Manufactured stone, which is essentially moulded and coloured concrete, has become increasingly popular, particularly for stone veneer applications.

Its main environmental impacts relate to quarrying. Modern Australian quarrying techniques include site remediation but stone sourced from overseas may be from quarries that do not have advanced environmental management.

The cost of stone masonry varies widely, generally according to the quality of the stone and the labour involved. Traditional stonework requires a high level of specialist skill, but stone masons can be found in all parts of Australia. You may consider stone building as a self-builder, but first seek advice from qualified masons and builders.

Photo: Getty Images

Timbercrete

Timbercrete is a relatively new lightweight composite masonry material invented in Australia. It is available in the form of bricks, blocks, panels and pavers. Made from excess sawmill waste from plantation timbers mixed with sand and binders such as Portland cement and a non-toxic deflocculating additive, it is cured using sun and wind and has a lower embodied energy than traditional fired bricks.

Two-and-a-half times lighter than concrete or clay, it has a higher insulation value than brick, concrete or earth masonry, with moderate thermal mass and a high fire resistance. Timbercrete is manufactured in a range of blocks and bricks varying in thickness from 90mm up to 300mm. A 200mm block has an R value of 1.02.

The material can be painted and internal faces do not need to be lined. It is available in a wide range of colours, textures, sizes or shapes that can be specified by the purchaser. It is not as brittle as clay or concrete and does not shatter. It can be used as a single skin building system and can be nailed or screwed like timber.

Photo: Peter Collier, Timbercrete

Photo: Peter Collier, Timbercrete

Glass blocks

Also known as glass bricks, glass blocks share some of the properties of both blockwork and glazing. They are made in modular units that can be built into walls and transmit light. Made from 2 halves of heat-proof glass pressed together, glass blocks can be set directly in mortar as part of a brick or blockwork wall. Although a wall or panel of glass blocks is essentially self-supporting, they are generally set in a frame, usually steel or aluminium (and sometimes uPVC), and fixed with silicone to help accommodate differential movement relative to the containing wall.

Glass blocks have higher thermal insulation values than double glazing and are approximately equivalent to double brick walls. In a recent innovation to improve thermal efficiency, a sheet of floating glass is set between the 2 halves of the block to create 2 chambers that are filled with argon gas, reducing thermal transmission by 50%. Glass blocks are recyclable.

Photo: Paul Downton

Buildability, availability and cost

Building with brickwork and blockwork has a long history in Australia, and there is a huge body of knowledge and experience on standards and techniques for these construction systems.

Clay and concrete bricks are manufactured throughout Australia and are available at competitive prices. Even in remote areas, bricks and blocks can be supplied at moderate prices due to the wide availability of truck transport and back-loading opportunities. Consider transport energy costs for any long-distance movement of heavy materials (refer to Embodied energy).

Brick veneer – the construction system of choice for most domestic builders – is one of the most economical ways of building in Australia. Lightweight framing is the main structural part of brick veneer construction. It is quick, uses no wet trades and allows roofs to be erected early in the building process.

Double brick or double masonry typically requires that the inside leaf (in the equivalent position to studwork in a lightweight timber or steel frame structure) is structurally sound before roof framing can begin. Double brick construction thus takes longer than brick veneer.

Reverse brick and masonry veneer uses trades and techniques that are familiar to domestic builders but are arranged in a different configuration. The external, lightweight leaf requires waterproofing treatment and the building’s openings require slightly different detailing. As a result, reverse brick veneer is generally more expensive than conventional brick veneer and there may be some differences in the building program that slightly extend construction time.

Solid brick and blockwork walls are mostly used for internal walls and generally the only buildability issues arise from their connection with other components of the building and impacts that may have on the construction program.

Appearance

Clay brickwork is available in a wide variety of natural colours and textures derived from the clay used in firing. The bricks can then be combined with cement mortar joints of various colours and finishes to create many different looks. Bricks remain stable and colour-fast and do not need to be rendered or painted. Clay brickwork is most commonly used uncoated to display the richness and texture of the material.

The colour of concrete bricks and blocks is usually light to medium grey – the colour of the cement used in their manufacture. Pigments can be added to the concrete mix to create other colours, but these may fade or weather over time.

Photo: Getty Images

Structural capability

Fired clay bricks offer high compressive strength. Both clay and concrete brickwork walls can readily support relatively high loads, such as suspended concrete slabs. Clay brickwork is commonly used in construction of up to 4 storeys and with suitable detailing can be used for loadbearing walls in much higher buildings.

Clay and concrete bricks are manufactured under close controls to the requirements of Australian Standard AS/NZS 4455.1:2008 Masonry units, AS/NZS 4456:2003 Masonry units and segmental pavers and flags — methods of test and AS 3700-2018 Masonry structures. These provide the means for determining the strength of clay brickwork walls when subjected to horizontal loads resulting from wind, earthquake or fire.

Concrete blocks come in a variety of densities, and should be matched to the required application. High-density blocks are generally made from cast concrete and aggregate, whereas lower-density blocks may use fly ash or cinder.

The voids in hollow concrete blocks can accommodate reinforcement rods (a typical detail for retaining wall construction) or be filled with a variety of insulating materials to improve their thermal resistance.

Source: Concrete Masonry Association of Australia

Durability and moisture resistance

Clay brickwork is extremely durable. The requirements for bricks, mortar, built-in components and reinforcement to achieve various levels of durability are detailed in Australian Standard AS 3700-2018 Masonry structures.

Although not completely waterproof, clay brickwork walls resist the penetration of rainwater, including wind-driven rain. Some moisture may eventually soak through the mortar joints. For this reason, external brickwork is generally constructed with a space separating it from the internal leaf in the form of brick veneer or cavity walling.

Clay bricks can be subject to fretting where the surface of the brick progressively spalls off. This is caused by water migrating in the wall and transporting salt to the brick surface where it forms crystals that grow in voids in the brick and break off from the brick surface as they expand. Appropriate use of damp courses and good detailing to avoid moisture penetration and build-up can eliminate most of the risk of fretting.

Concrete bricks are designed to perform in a similar way to clay bricks and have a surface finish that resists the penetration of rainwater. As with clay bricks, general detailing and construction should seek to eliminate moisture penetration, typically with cavity walling.

Concrete blocks are porous and need to be treated, coated or covered to prevent moisture wicking through the material.

Detailing for brickwork and blockwork needs to incorporate:

• damp-proof courses
• flashings
• weep holes.

Thermal mass and insulation

Clay brickwork and concrete blockwork both have high thermal mass. When used in conjunction with passive design to suit your climate, thermal mass can improve the thermal performance of your home and reduce heating and cooling costs. However, inappropriate use of thermal mass can reduce comfort.

Clay and concrete brickwork have low thermal resistance and therefore relatively poor insulation values. Combined with internal and external air films and a cavity, they achieve moderate thermal resistance.

The thermal resistance of brick and blockwork walls, including veneer or cavity construction, can be greatly increased by adding foil or bulk insulation. Wall insulation should be accompanied by appropriate detailing to avoid thermal bridging through window and door frames, by radiation through window openings or by convection through leakage.

Due to their mass, brick and blockwork walls provide excellent sound insulation, particularly for low frequency noise.

The National Construction Code (NCC) has specific requirements for sound attenuation in multi-unit dwellings which can be satisfied by providing 2 leaves of 110mm clay bricks with a cavity of 50mm between leaves and a 13mm cement render on each outside surface.

Thermal resistance (R; m²K/W) of cavity brickwork

Source: Adapted from AS 3700-2018, Masonry structures.

Fire and pest resistance

Clay bricks and concrete blockwork both have excellent fire resistance. Their design for fire is covered by Australian Standard AS 3700-2018 Masonry structures. Clay and concrete brickwork and blockwork does not burn when exposed to bushfire and can help protect the more combustible items inside a house.

Clay and concrete brickwork and blockwork consist of dense inorganic materials that do not harbour pests. Termite resistance may be achieved in a variety of ways, including proprietary termite barriers developed for use with brickwork.

Design of clay brickwork for fire resistance

Source: Adapted from AS 3700-2018, Masonry structures.

Toxicity and breathability

Clay bricks are inert and are not prone to giving off volatile materials. Clay brickwork and its constituents are nontoxic; however, when handling cement (used in the mortar) or cutting brickwork with a masonry saw, observe the manufacturer’s safety procedures to minimise the risk of skin irritation and lung damage.

Similarly, concrete bricks and blocks are inert, do not give off volatile materials and are nontoxic once manufactured. The same provisions apply to safe handling of cement and cutting procedures.

Environmental impacts

The manufacture of bricks and blocks in either clay or concrete uses energy, but the investment of embodied energy is repaid by the longevity of the material. Masonry homes have a long life and low maintenance requirements and are highly recyclable, adding to their potential as a sustainable form of construction.

Clay bricks can often be reclaimed for reuse when a building is demolished. After cleaning they can either be directly reused as bricks or crushed for making path and road surfaces.

Hydrated lime added to cement mortar can improve its plasticity, workability and weather tightness. Greater weather tightness and impermeability can help to reduce condensation in walls. Lime mortars also make recycling and cleaning of bricks for reuse much easier.

The use of fly ash in some concrete block manufacture replaces the energy-intensive material of cement with a waste product from power stations.

Eco-comparison websites can help you select options with low environmental impact (refer to References and additional reading).

Sound insulation

Due to their mass, brick and blockwork walls provide excellent sound insulation, particularly for low frequency noise.
The National Construction Code (NCC) has specific requirements for sound attenuation in multi-unit dwellings which can be satisfied by providing 2 leaves of 110mm clay bricks with a cavity of 50mm between leaves and a 13mm cement render on each outside surface (refer to Noise control for more information).
 

Design and detailing

Loadbearing walls

Critical to the function of any building is the ability of the walls to support suspended floors in addition to the roof and walls in the storeys above. In most cases, concrete floor slabs dictate the use of loadbearing masonry. Industry bodies provide comprehensive manuals with charts and tables for the design of loadbearing masonry walls.

Openings

Most commercially available doors and windows are manufactured to be compatible with standard brick sizes, in either veneer or cavity construction. Information on the required sizes of openings and fixing information is available on the internet and from window manufacturers.

Finishes

External face clay brickwork capitalises on the broad variety of colours, textures and finishes of Australian bricks, mixed and matched with coloured or plain mortars in struck, ironed, pointed, or raked joints. Clay brickwork is often used for internal feature walls and is a particularly appropriate approach for reverse brick veneer construction.

Concrete bricks are available in a wide range of colours. Although concrete blocks can be used as facing material, they are usually rendered to improve both aesthetics and their resistance to water penetration.

Internal brick and blockwork loadbearing walls, firewalls and acoustic partitions are usually painted, rendered or sheeted with plasterboard.

Typical details

The National Construction Code provides the regulatory framework for the design and construction of masonry. Australian Standard AS 4773.1-2015 Masonry in small buildings – Design, sets out minimum requirements for the design of unreinforced and reinforced masonry for use in small buildings and specifies requirements for the design and specification of masonry with a leaf thickness of at least 90mm in buildings of Class 1 and Class 10a.

Brick and blockwork industry bodies and many of the manufacturing companies publish design manuals and standard details.

The build process

Construction process

There are 4 main ways to use bricks and blocks to make walls. Each method has its environmental and economic merits and it is important to understand the reasons for choosing any given method in building your home.

• Brick veneer – A commonly used approach in which bricks form the external skin of a timber- or steel-framed home (refer to Lightweight framing). Conventional brick veneer construction places the high mass of brickwork on the outside of the building. This creates a long-life, low-maintenance exterior. However, in this arrangement the bricks contribute little to the thermal performance of the building.
• Reverse brick veneer – Bricks form the internal skin of an insulated, framed home. Reverse brick veneer takes advantage of brick’s thermal mass properties to improve thermal performance. It can produce high-performing buildings with lower than average energy demands for both heating and cooling.
• Double brick – Consists of 2 layers (or leaves) of brickwork with a cavity. The cavity reduces thermal transmission and prevents moisture being transferred directly from the outside wall face to the interior of the building. The internal leaf, or skin, may be plasterboard-lined concrete blockwork, with the external skin in facing brick. The leaves of double brick are joined with ties.
• Solid brick – A high thermal mass construction mostly used for internal walls. Solid brick or blockwork walls deliver good loadbearing capacity along with substantial thermal mass to provide a unique combination of structural, thermal and aesthetic benefits. Internal walls of solid brick or blockwork provide well-located thermal mass that can be either self-supporting or load bearing.

Photo: Crosby Architects

Footings

For clay and concrete brickwork houses, concrete footings and concrete raft slabs should comply with Australian Standard AS 2870-2011 Residential slabs and footings. This standard is based largely on the behaviour of clay brickwork houses. Footings for brick veneer buildings are generally smaller than the corresponding footings for cavity brickwork.

For other brick and blockwork buildings, concrete footings and concrete slabs should be designed and constructed in accordance with Australian Standard AS 3600-2018 Concrete structures.

Frames

For brick veneer and reverse brick veneer homes, frames provide the required strength and stability. Timber frames should comply with Australian Standard AS 1684 Residential timber framed construction, and steel frames should comply with Australian Standard AS 3623-1993 (R2018) Domestic metal framing.

Fixings

Major anchorages (such as roof tie-down anchorages) should be built into brickwork or blockwork during construction. In areas of high wind uplift, anchorages should pass down the cavity and be tied into supporting concrete slabs or footings. Windows and doors may be built into walls by setting the attached ties in the mortar joints.

Minor anchorages (for example, hanging light loads from walls) may use any of the wide range of commercially available proprietary mechanical or chemical anchors. These anchorages are set in holes drilled using a hammer drill of the appropriate size. Higher anchorage strength can be achieved if set into the bricks or blocks rather than the mortar.

• Eco-comparison websites
  –    Australian National Life Cycle Inventory Database
  –    Building Products Information Rating
  –    Ecospecifier Global
  –    Environmental Product Declaration Australasia
  –    Global GreenTag
  –    Good Environmental Choice Australia
• Australian Stone Advisory Association.
• Hipages Group.
• Cement, Concrete and Aggregates Australia.
• Concrete Masonry Association of Australia.
• Think Brick Australia.
• Timbercrete.

Learn more

• Explore Design for climate to find out how appropriate design can help you to save energy and money
• Read Construction systems to get ideas about building options for your home
• Look at Insulation for more ideas on how to slow heat transfer through your home

Authors

Original author: Cathy Inglis

Contributing author: Paul Downton

Updated: Paul Downton 2013, Department of Industry, Science, Energy and Resources 2020