In the construction industry, there is a plethora of materials that can be used naturally. These materials can be reused or recycled, conserving energy and reducing carbon emissions in the production process.
Some common natural building materials include clay (in cob walls), sand and straw, wood (cordwood or timber frame/post-and-beam), cork, hemp and jute. Most of these natural materials are breathable and avoid releasing toxic chemicals or volatile organic compounds during the build process.
Earthbags
Earth has a long history as a building material, from the adobe homes of the Southwest to the rough shelters of military bunkers. A modern twist on this ancient practice is a sturdy process called earthbag building, which uses polypropylene bags filled with a mix of clay, sand and silt to make walls that can be used to build everything from tiny huts to full-sized houses.
The key to earthbag construction is a simple rubble trench foundation that eliminates the need for expensive concrete or other forms of footings. Builders also use site-available earth as fill, although some prefer to buy reject soil from a local gravel centre that contains the right ratio of sand and clay. Lightweight volcanic stone (such as scoria and pumice), perlite, rice hulls and vermiculite can also be added to improve insulating qualities.
Building with earthbags is inexpensive and very durable, if plastered correctly. It can be used for both permanent and temporary structures, including houses, barns and cisterns. It’s also a great option for bermed and underground dwellings like earthships, as well as retaining walls and water-resistant basements.
Another benefit of using natural materials in the shell of a home is that they are sourced from renewable resources. Wood, straw and hemp are sourced from plants that absorbed carbon dioxide while they were growing, so reusing them as insulation will help to mitigate greenhouse gas emissions. Additionally, many of these materials are reusable, recyclable or bio-degradable at the end of their life, unlike concrete which can be toxic and pollute the environment for centuries after it’s been put in place.
Cordwood
Cordwood construction, also known as stackwall building or log-end masonry, is one of the most common natural building techniques. It utilizes what would normally be kept aside as firewood, or the ends of large logs left over from sawing a tree, to create walls with high insulation value and good thermal mass. Portland cement mixed with sand and sawdust serves as the mortar between the courses of log-ends. The result is a warm, sturdy and attractive wall system.
The best wood for this type of building is rot resistant, such as spruce or cedar. But it can be built with almost any hardwood that is seasoned and cut in short lengths. It is important to remember that the energy used to haul the cordwood over long distances will be a factor in a home’s embodied energy, so it is better to use wood that is locally available.
Like earthbags, cordwood can be both an insulation and a structural material. It is often built inside a timber frame or post-and-beam structure. This allows for high strength and durability, even in earthquake prone areas. Like rammed earth, cordwood construction is very energy efficient, as the tight wood-mortar seal keeps cold air out in winter and heat in in summer.
Another method of using natural materials for building is straw-bale construction. Straw bales work well as a load bearing material working alongside a timber frame to provide highly effective insulation that exceeds Building Regulation standards. In addition to the insulation value of straw bales, they offer a degree of thermal mass due to their considerable weight and cellular structure. The straw is also a breathable material that regulates the internal air quality and keeps damp at bay.
Natural Stone
Natural stone is one of the most time-tested construction materials in existence, gracing some of the world’s most famous structures like the pyramids of Giza and the Parthenon. Its durability, versatility and unique visuals make it an ideal choice for a wide range of interior and exterior design projects including building cladding, floor surfaces, paving and more.
Different types of rock have different characteristics, so deciding on the right type of stone to use for your project depends on what you want to achieve. For instance, basalt, sandstone, and granite perform well in large scale infrastructure construction, while travertine and limestone are more suitable for interior design. In addition to the physical properties of a stone, its color and surface texture will also influence its suitability for a particular application.
When designing a green building with natural stone, it is important to consider the embodied energy of the material. This includes the energy used in quarrying, transporting the blocks to the plant, cutting and shaping the stone into slabs and tiles, and finally delivering the finished product to the building site.
Natural stone typically has low embodied energy, making it an environmentally friendly option for building construction. However, the embodied energy of different natural stones varies depending on their composition and the manufacturing process. For example, limestone has a lower embodied energy than marble, which has a higher embodied energy due to its high compression strength.
To get a better understanding of the unique characteristics and sustainable benefits of natural stone, connect with your local stone supplier for samples of the stone you are interested in using. A reputable supplier will have an extensive portfolio and can help you create a bespoke and cohesive stone solution for your project. They can also provide technical backup, training and guidance on the latest Government legislation, building standards and slip resistance.