The techniques of building houses from natural materials have not changed much since several hundred years ago. Houses made of clay, wood and stones are built in the same way as before, only the tools changed. Straw buildings have only been built for a hundred years, and the methods of their construction are getting better and better. Designers pay attention to the energy efficiency of all buildings. It can also be obtained by building houses in the new hemp concrete technique. A mixed technique of building from natural and waste materials produces dugouts, or earthships*. An additional curiosity is the use of paper in construction.
Walls made of rammed earth are made with formwork. The clay is placed between two walls of boards spaced apart to the thickness of the future wall. Clay is poured between the boards and compacted mechanically or with special rammers. When the first layer of clay is dry, the next layer is poured and rammed again. The formwork is taken apart when the wall is ready. This method was used in various regions of the world to build houses, ramparts, castles, and in the Netherlands to build dams against sea waves. Nowadays, it is used in housing construction, museums, and ecological centers. Walls made of rammed clay are thick, do not need additional construction, keep warmth and constant humidity in the rooms, no dust settles on them, and they create a healthy microclimate inside.
artistic school built with rammed earth
In Poland, wooden log houses are best known in Podhale. In the past, houses were built from logs cut in a sawmill. Logs were also cut into boards. The houses were sealed with moss, grass from wet meadows, rope (Scandinavia) and wood wool or wood shavings. Building like that was cheaper. Now large houses, inns and hotels are built from full logs. The logs are placed (on the foundations and damp proof insulation) on top of each other, and the point of contact is hewn so that the logs connect. The walls can be single layer or composed of several layers for better thermal insulation. The outer wall is made of logs, the inner one is made of boards, and between them there is insulation, for example, made of mineral wool. The walls of the house are connected at the corners in pivots or locks specially cut by a carpenter. The internal walls are attached to the external walls. All walls form a strong, flexible, wind-resistant structure, prepared as a base for a roof, which also consists of several layers: roofing (made of tiles, shingles or reeds), insulation and soffit, that is, internal finishing of the attic.
Fieldstones are mostly granite, gneiss, porphyry and quartzite. Long ago, glaciers crushed mountains and carried stones to fields. When they melted, they left behind scattered boulders, smaller rocks and gravel. Different origins of the stones are responsible for the variety of colors: gray, red, reddish, navy blue, greenish, brown, yellowish, etc. The stones are very resistant to weather and so they are used as elements of terraces, house walls, and ponds in gardens. Houses can be built of whole stones, using lime or clay mortar. You can split the stones and then cover the facade of a house or a wall, terrace or path.
A straw bale is a cube of straw made of stalks (e.g. wheat, rice, rye or oats) pressed during the harvest by a combine. We can use straw cubes to build house walls, leaving openings for windows and doors. The wall is built on a horizontal wooden structure, called the bottom rim (foundation), placed on a foundation sunk into the ground. A material to protect the wall against moisture is laid between the foundation and the rim. A house made of straw cubes can be built in two ways: the wall may be made of only straw cubes (it is called a self-supporting structure) or bales can be used to fill a wooden structure. The walls of straw bales are fastened with vertical pins of bamboo or hazel so the cubes do not move. Straw houses have roofs (eaves) protruding beyond the wall to prevent them from getting wet in the rain. In cooler climates, the straw walls are plastered with lime outside and with clay inside.
We take part in the construction of a clay house virtually, from digging for foundations, through the foundations, bracings and walls, to the green roof.
How to prepare a mixture of clay, sand and water to plaster or repair a house wall?
a straw bale house with a wooden construction
without an additional wooden support structure
Hemp concrete is a mixture of hemp shives (the woody part of the hemp stem separated from the fibers) with lime and water. It is mixed in the right proportions in a concrete mixer. Then, the finished mass is poured layer by layer into formwork made of boards, then gently tamped with a machine or manually with a rammer. Each layer must dry before the next one is added. The entire wall dries and hardens in the formwork, and then the boards are removed. The load-bearing element (which keeps the wall vertical) is usually a wooden structure inside the hemp wall. The roof rests on this structure. Hemp concrete has very good thermal insulation properties, it does not need additional insulation, it regulates the humidity inside the building well. Outside, the building can be finished in many ways: with clay, lime plaster or boards, called shuttering.
The owner decided to renovate her old house using the new technology. After taking down the walls, the company made new hemp concrete walls on the wooden structure. There are solar panels on the roof.
Paper itself is not a natural material, but can be made from natural plant materials. It was present in Japanese architecture as early as the 8th century. It was made from shrubs and trees: mulberry, hemp and gampi, and is called washi. In Japanese architecture, it was not a construction material but was used to fill house walls. The sheets were attached to wooden or bamboo frames that could be slid over wooden rails. The frames were used to create external walls - then they had a double layer of paper - and internal ones. By moving the frames, it was possible to obtain a different layout of the rooms or access to the garden. The paper was white and allowed light to enter the house. It was not transparent, so the light was diffused. The outer frames with light paper were called shoji and they were the lower part of the movable walls. In winter, the houses were heated with charcoal. Paper was not resistant to moisture, but in Japan, houses had large eaves (the part of the roof that protrudes beyond the walls) and such walls were not exposed to rain. In Europe, on the other hand, paper was used to make windows, but it was soaked with oil to make it resistant to moisture. European houses had narrow eaves and rain fell on walls and windows.
Today, paper is still used in Japanese homes, but only in interior walls. Such walls are called fusuma.
Earthships are buildings that use natural building materials (wood, stone) and interior finish (clay), natural energy sources, and recycling - secondary raw materials, waste. For example, car tires with compacted soil, used to build walls, are waste. Many buildings are built on slopes and retaining walls which protect the house from landslides are built of tires. There is also soil on the roof, with planted grass and bushes. As a building material, earth protects buildings against cold and heat. Earthships use renewable energy sources from the sun and wind (heating and water heating), a separate biological sewage treatment plant, installations for collecting and storing rainwater, installations for obtaining "gray" water (water used once for washing and then cleaned in a home treatment plant and used to flush toilets) which is then reused in the home and garden. They have their own wells and greenhouses where vegetables and fruits are grown. Such houses are self-contained. We call them autonomous.
The first earthship in Poland in Mierzeszyn near Pruszcz Gdański