The use of natural materials in building construction is a key aspect of greening your home. These materials are breathable and avoid releasing toxic chemicals into the atmosphere.
Conventional materials like plastics, unsustainably harvested wood and Portland cement based mixes and paints that off-gas volatile organic compounds are all avoided in natural homes. Eco-friendly alternatives include mud, earth, straw bale, coir and hemp or jute fibres.
Stone
Stone has been a staple in building construction for centuries, and for good reason. It’s durable, visually appealing, and can be carved into an array of shapes, forms, and textures to suit architectural designs. In addition, it can help to regulate indoor temperature and offer energy efficiency.
Stone can be sourced from the local area for minimal environmental impact. It can also be recycled and repurposed to save money, time, and resources. For example, reclaimed limestone can be used to make sidewalks or patio tables rather than being sent to a landfill.
Lola Ben-Alon is a professor at Columbia University’s Graduate School of Architecture Planning and Preservation (GSAPP) where she directs the Natural Materials Lab. Her research focuses on socially and environmentally sustainable building materials, construction practices, and engineering-architecture collaborations. Her expertise is in natural, earth-based and bio-based building materials, their manual and digital fabrication, and life cycle and supply chain assessment. She’s also a passionate advocate for promoting diversity in the field of architecture. She works to create opportunities for people of all backgrounds to engage in hands-on, socially and ecologically responsible construction.
Cork
Cork is a natural material that has been found to be incredibly useful in the building construction industry. It has a very low ecological footprint and complies with many of the Green Building requirements.
It is harvested without harming the tree, which can be repeated every 9 to 12 years, and is an extremely durable material that can be recycled or left to decompose naturally. It is also waterproof and contains a natural substance called suberin that acts as a fire retardant.
It can be used for flooring and wall panels, which are easy to fit together and incredibly light. This makes them easier to transport, which could help reduce the overall carbon footprint of the build. It has one of the lowest heat conductivity rates of any natural material and is a very good insulator, absorbing sound and vibration. It is also mould-resistant and has a pleasant smell. One couple in London has used cork cladding for their extension, which they say has made their home more comfortable and cost effective to heat.
Clay
Natural materials are substances sourced directly from the environment, including plants and animals. These are not altered significantly by industrial processes, preserving their original properties and characteristics. They can be re-used or bio-degraded at their end of life, making them a sustainable and eco-friendly option for building construction.
The main types of natural materials in use include timber, clay, stone, and straw. These are used to build a wide range of buildings, from walls and roofs to terraces and garden spaces. Many of these natural materials have been in use for centuries, but new developments are bringing them into the 21st century. These advances are improving the quality of these materials, making them more cost-effective and easier to work with.
Another type of natural material that is proving to be very popular in modern green construction is cob. This material is made by blending together clay, sand and gravel, and other organic waste such as plant debris and hay or straw. It is a highly durable and versatile building material, suitable for almost any kind of house design.
Straw Bale
Straw bales are a natural, socially acceptable, affordable building material. People enjoy a sense of empowerment in participating in the construction process, reminiscent of barn raisings or quilting bees. This is a powerful experience for women and men of all ages and abilities, especially because it is a hands-on building technique that is not intimidating to inexperienced builders.
While it takes longer to build a straw bale home, it is an excellent alternative to conventional wood framing for homes in mild climates. The walls are shaped by stacking and tying bales together, like bricks. The resulting walls can be load bearing or non-load bearing, and are often finished with plaster to protect them from rain, fire, and pests.
In addition to the frame, a vapor barrier is usually placed in a straw bale wall to prevent moisture penetration, which can lead to mold and mildew problems. Generally, doors and windows are set into the bales or frames before they are plastered to avoid distortion. Depending on the location of the straw house, a foundation may be required for stability.
Insulation
A building’s insulation is a critical part of its energy efficiency. It reduces heating requirements and reduces the need for fossil fuels, which has positive impacts on climate change. However, not all insulation materials are equal. Choosing the right natural material is important in terms of its sustainability, durability and cost-effectiveness.
Stone, wood and clay are all natural materials that have been used to construct buildings for millennia. But they each require different amounts of human intervention to turn them into usable construction materials. Wood requires little processing, while clay is difficult to work with and must be turned into bricks in a long process of wining, shaping, firing and drying.
Sheep’s wool is a natural fibre that’s an outstanding home insulator – its fibrous structure forms millions of tiny air pockets that trap air. Another natural insulation is rammed earth, which uses accurate proportions of sand, clay and gravel along with a stabiliser. It is an ancient and sustainable technique. Other alternatives are papercrete (which is made from recycled newspaper) and hempcrete, which uses lime, sand and the plant’s fibres.