Clay screed: properties and applications

Clay screed is an interesting ecological alternative that has been rediscovered in recent years and is being used more and more frequently. You can read about the possibilities of using clay screeds and the characteristics of this natural material in this article.

Ancient building material

Clay is one of the oldest building materials of humanity. Even the soils of ancient megalithic plants, which date back to the Neolithic Age and are much older than Stonehenge, already contain loamy soils that are very similar to today's clay screed.

Not for nothing is the human being itself originally made of clay in many ancient creation myths of different cultures.

Clay consists of clay, sand and quartz flour. It is a weathering product caused by the weathering of rocks.

High ecological building material

Clay does not have to be made with a lot of energy, but is available as a finished natural material in most places. This already significantly improves the eco-balance compared to building materials such as cement produced artificially and with a high CO2 cost.

Clay can even be recycled - so it has an unbeatable sustainability, so no building material reached.

Clay also has a very high heat storage capacity, which still increases as clay screed through the aggregates. Also, the sound-absorbing properties of clay are very good.

Clay is an extremely durable and resilient building material, as some still almost perfectly preserved ancient buildings prove, which are already several thousand years old.

Processing of clay screed

Clay does not chemically bind like cement, but becomes hard only when dried out.

Due to the high loss of water, clay screed tends to crack. To prevent this, certain additives - such as animal hair or straw - come to the clay. They make it more resistant to cracking.

Loam screed is easily made by mixing the clay with aggregates. The clay content in the clay determines how "fat" or "lean" the clay screed fails. Depending on the predominantly existing minerals in the clay, the color of the clay screed can be quite different - but this does not matter for durability.

Clay must be "tamped" so that cracks no longer occur. Loam screed is simply applied to the background layer and tamped until no more cracks occur.

Effects on the indoor climate

Clay is sensitive to moisture. Since it only physically dries up by the evaporation of the contained water, it is changed in its consistency when it is exposed to moisture.

But it also offers the possibility of an excellent moisture regulation. It can absorb and release humidity. Together with the aggregates, its heat storage capacity is remarkable.


As a screed clay screed can be used easily in most cases. It is also available as finished bagged goods, often already mixed with aggregates. In terms of price, clay screed is much higher than conventional screed mortar.

Other uses of clay are as clay plaster (without aggregates) or clay color. However, loam is not suitable for outdoor use. During drying, care must always be taken that drying takes place as quickly as possible (possibly with additional heating).

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