Why build with clay?
People have been using clay as a building material for thousands of years. To this day, as an ecological building material, it creates comfortable living spaces.
It is increasingly taken for granted that the home environment should also be designed to be natural. This matters for well-being, as people are spending more and more time indoors. The designed environment has an ever greater influence on people. With its many positive properties, clay gives our living spaces a climate in which we feel comfortable.
Advantages of clay coatings
Clay plaster actively regulates the indoor climate
Due to the ability to absorb moisture from the indoor air and to release it again, clay can buffer fluctuations in air humidity.
Clay and indoor air
Along with moisture, clay also absorbs odours and pollutants. It breaks them down and binds them firmly. One gram of clay minerals has a surface area of about 800 m².
Clay preserves wood
The equilibrium moisture content of clay is so low that it always draws moisture out of the wood, which gives the wood perfect protection against pests and fungi.
The primary energy of a load-bearing clay plaster is almost zero
The production of earth-moist clay is very simple and requires only less energy, the gray energy (primary energy) of earth building materials is low. Transport energy can still be saved because of its frequent occurrence.
Clay is a natural product
Clay needs no chemical additives and is therefore ideally suited to people with allergies and people with MCS.
Clay can be reused again and again
The low primary energy consumption can be further improved by using it multiple times. Clay does not bind chemically and is mixed with water to make new building material.
Clay is a joy to work with and to live with
Working with clay is stimulating and inspiring for the mind, and living in clay rooms is calming and relaxing.
Clay can be stored indefinitely
Clay is thousands of years old and has been stored in nature for ages. Clay can be stored for centuries without spoiling.
Clay plaster has excellent heat transfer properties
Clay in combination with wall heating is extremely effective in transferring heat. Compared to lime, you only need half of the installed heating pipe for the same amount of heat.
Hand application of clay plaster
Earth building is relatively easy to learn. Fortunately, every clay wall or ceiling starts with a base plaster. This plaster layer is ideal for practising and gaining your first experience of earth building.
In old clay houses, the clay walls and ceilings we want to work on are usually so uneven that the first step is to fill the rough unevenness and holes in the substrate with clay plaster or universal plaster. A homogeneous layer is then created on the wall with the classic clay base plaster. It can be applied either by hand or with clay plastering machines. Good steel tools are helpful for applying by hand, and also for the subsequent smoothing and compacting work.
Three-layer clay plaster
A good clay plaster always consists of three layers. The first layer is a base plaster. It is applied to stable substrates that are otherwise suitable. It evens out irregularities and builds up the required layer thickness.
In most cases, a mesh layer is embedded in the second coat. These reinforcing meshes are made of jute, plastic or glass fibre. Clay plaster on masonry made of mixed bricks, on reed plaster bases, on half-timbered walls, on straw bales and on board materials such as soft wood fibre boards or OSB panels with reed matting absolutely requires the mesh. The jute mesh, reinforced without plastic, is the ecological alternative to synthetically manufactured products, but requires a little more experience.
A base plaster is usually used for the first two layers. When plastering board materials, the first base plaster layer can be omitted. Instead, a fabric layer can be applied directly to the board using clay adhesive and reinforcing mortar.
Complete clay plaster
Once the clay base plaster has dried, the finishing plaster is applied. Depending on your personal taste and preference, this can be a fine clay plaster, a premium clay plaster or a clay finishing plaster. A finishing plaster should be floated off, as this compacts the structure and makes the plaster stronger. If the job is carried out cleanly, no sanding is required.
If a finishing plaster is worked with a sponge float, using two different sponge floats is recommended. On the first day, work with a very fine sponge float; once it has dried, go over the surface again the next day with a coarse sponge float and wash off the sand lying on the surface. The surface is compacted slightly once again and is nicely stable.
The final coat of plaster can now be painted or given a fine finish. One option is surface treatment with a clay skim coat. These fine-grained earth building materials can be sanded, and with a little practice you can achieve surfaces of Q4 quality.
Applying clay plaster by machine
Above a certain size of area to be worked, using a plastering machine is worthwhile.Above a certain size of area to be worked, using a plastering machine is worthwhile.
Once the area to be worked reaches a certain size, using a plastering machine is worthwhile.
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Time-saving
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energy-saving working
With larger quantities of clay, the extra mess on site, the additional work of masking adjacent surfaces and the greater logistical effort quickly pay off. Besides large plastering machines, some of which can mix, pump and apply the material, there are of course also more modest tools, such as mixers and paddle stirrers.
