Sustainable and Renewable Construction Methods
Natural building refers to the primary building material used in the construction. Earth is the basic building material for most of the world’s population. The materials used in natural buildings are clay and sand. When mixed with water and straw, they form cob or clay blocks. Other used materials are wood straw, bamboo, and stone. Materials avoided by natural builders include portland cement-based mixes and Autoclaved aerated concrete, paints, and steel. Natural builders can apply many different techniques.
Adobe construction is used for centuries by people all around the world. Adobe is nothing more than clay and sand mixed with water. Three necessary materials are used to form an adobe (clay, sand, and water), and sometimes, the fourth material is added to stabilize the mass. Once mixed, it is left to dry. In locations with harsh weather, the adobe is secured with a bit of cement to keep it held together. The mixture is then allowed to dry into bricks that can be stacked to form walls. The blocks are poured into molds and dried, and the adobe can encompass nearly any shape or size. The optimal proportions of clay and sand to bind the material together and to prevent cracking of the bricks are between 15% — 30%. Adobe buildings usually have broad eaves and big foundations. It is a slow transmitter of heat or cold, but it is not a good insulator. Buildings made of sun-dried earth are typical around the world.
Cob is a mix of clay, water, and sand. Mixing is done manually through mushing by foot and flopping it around, but it can also be mixed by machine. Without some fiber, cob will lose most of its strength. Cob walls are build up from the foundation in one solid piece with no forms, bricks, or framework. Cob is the most straightforward and least expensive building technique, but a very labor-intensive one. It is versatile, and It can be shaped into any form. One-third of the world’s population lives in some cob dwellings today. Cob uses low-cost materials, is fireproof, and resistant to seismic activity. The cob walls provide excellent thermal mass, which keeps warm in winter and cools in summer days.
3. Rammed Earth
Earth is the essential building ingredient, and besides piling or placing the material in the form of bricks or some other shapes, it can be compressed into place by mechanized equipment. Rammed earth is made of soil that is compacted, which makes it very strong and durable. Rammed earth walls are reliable, and stone-like with great benefits for the environment. Optionally, other natural materials can be used to reinforce the earth wall. Rammed earth is used for thousands of years as a primal building technique.Rammed earth walls are molded by hammering sub-soil into movable, forms with manual labor or machines. A mixture of around 70% gravel and sand and 30% clay is optimal. Around 5–10 inches of the mix is placed inside the desired forms and hammered until compacted, and the process repeats until the desired height is reached. After the forms are removed, the made wall is robust and can last over hundreds of years.
Cordwood constructionis a building method in which short logs are piled across to build a wall, using mortar to secure them. Cordwood relates to the small pieces of wood usually seen in a fireplace. But instead of burning them up for fuel, it is lined up and held together by mortar. This technique uses local materials at a minimal cost. Cordwood homes are attractive for their visual appearance and easy construction. Wood accounts for about 40–60% of the wall, the remaining portion consist of a mortar mix. The cordwood becomes infill for the barriers between timber posts. Cordwood construction can be combined with other methods. It has a high thermal mass, which helps to reduce variations in temperature. It also has a high insulation property, so it makes an excellent building material. It does require mortar, but cob can be used rather than cement if needed.
5. Timber framing
Much like the earth, wood is another building material that is abundant and reliable. If used from a source that regenerates their forests, it can be an extremely sustainable building material. Traditional timber framing is the method of constructing structures of heavy timber jointed together through various joints, with lap jointing, and tenon joints. It was the standard model of construction in northern Europe until the 19th century. Timber framing uses a bent, which is structural support consisting of two posts, a tie beam, and two rafters. These are connected through joinery. To become an excellent craftsman and able to construct durable building with this method, one must understand the fundamental aspects of the bent. This method is entirely natural methods of building with heavy timbers, capable of creating large structures using carefully arranged and joined timbers. The use of timber framing offers many aesthetic and architectural advantages. Buildings are quickly erected, and if properly engineered, timber framing provides good seismic protection.