In South Africa, there is a rich historical and cultural precedent for building with earth. This long thread of indigenous knowledge of earth building is at risk of being lost, however, as it is increasingly rejected in favor of bricks and concrete. Recent developments in the use and understanding of building with earth have redressed many of the perceived disadvantages of earth buildings related to durability and maintenance. Earth building can potentially offer all the comfort, durability and aesthetic requirements sought in conventional construction, but with much higher ecological and social value.
For the past 20 years, Tlholego has been a laboratory for methods of earth building. One key focus area is sun-dried earth bricks with lime sand plasters as a material that we believe offers particular ecological, social and economic value in a South African context. Earth brick construction is one of the oldest forms of earth building, dating back at least 9,000 years. South African communities still retain extensive traditional knowledge and experience in these methods.
There are several layers of value embodied in the use of earth as a building material:
• Cost-effective: Assuming the earth comes from on-site and is of adequate composition, earth bricks cost virtually nothing to make (excluding labour), making them affordable to the wider population than masonry bricks and cement. Earth brick buildings don’t need to be framed out in timber or reinforced with steel, so require less additional financial input in their construction.
• Accessible: Because suitable earth can also be found in 80% of places, it is a highly accessible and inclusive building material—particularly in rural areas.
• Adaptable: earth bricks can easily be adapted to locally specific contexts. They can be shaped and sized to meet different building designs, plastered (or not) and finished in myriad ways to achieve a high level of aesthetics and durability. There is great scope to the creative ways that earth brick can be incorporated into building projects.
• Low embodied energy: As a building material, earth bricks have a very low embodied energy because they don’t require energy-intensive processing and don’t need to be transported long distances. No gas or electricity is needed to make earth bricks, which rely instead on energy from the sun. Earth is a renewable natural resource, and its use in construction reduces the extraction of non-renewable resources.
• Safe: Unlike many industrial building materials, mud bricks don’t contain any chemicals or hazardous materials that are potentially harmful to builders, inhabitants, and the environment.
Rucore, together with the Tlholego Learning Centre, has worked with Brian Woodward, from Earthways, Australia, a world leader in low-cost owner-built housing, to develop the Tlholego Building System (TBS), a sustainable housing system for South Africa.
The TBS combines the principles of sustainable building systems with natural waste treatment and the Permaculture approach for designing food self reliance to produce a high quality, low-cost sustainable housing system for South Africa. Although the system was conceived as a solution to the low end of the housing market it is in fact applicable to all sections of the housing market. It is also flexible enough to accommodate conventional building materials.
The Tlholego Building System, a flexible, owner-built, low-cost, housing system produces low-cost housing without the deficiencies of the normally accepted model as well as significantly addressing environmental and resource problems not usually considered.
• Flexible: Low-cost housing systems and flexibility are usually seen to be mutually exclusive. Cost constraints are often said to dictate standard designs and standardization of materials. This need not be the case. Limits can be set to the degree of flexibility, within a range of low cost alternatives for each element of the building (i.e. footings, walls, floors, roofs, windows, doors, etc). The system allows for the addition of extra alternatives, as new materials, new building techniques, or new building standards are developed. If the cost implications of the different alternatives are clearly spelled out, then the owner builder can make an informed choice, within a certain cost structure. This choice may be between different materials, based on cost or availability. The choice may be between quality or quantity – a larger, lower quality house or a smaller, higher quality house. Flexibility should also facilitate staged construction and/or extensions at a later date, depending on availability of resources.
• Owner built: The idea of using the sweat equity (labour) of the end-user of the building, to reduce costs is not new. Generally up to 50% of the building costs can be saved by owner building even when using conventional materials. The degree to which savings can be made is dependent on the skill of the owner builder and/or the degree of skill needed for particular building materials or techniques. Choosing materials and techniques particularly suited to the owner builder (i.e. easy to use or learn to use) will increase the amount of money saved. The amount of cost savings can also be increased by careful selection of low cost materials, which can be made or collected by the owner builder. While this building system is ideally suited to the owner builder, it is equally well suited to support the development of small and micro enterprises.
• Solar design & thermal mass: It is generally accepted today that housing designed with good thermal performance, includes the basic concepts of passive solar design. One of the basic principles of passive solar design is the use of wall materials of high thermal mass in order to mediate the extremes of temperature. These high thermal mass materials include burnt brick, concrete, stone, and earth, often referred to as masonry.
Please contact firstname.lastname@example.org for more information. Rucore has available, at a nominal cost, documents on the Tlholego Building System, its application to compost toilet construction and guides for three low cost house designs.