Clay plaster: the disadvantages of the natural building material

Clay as a building material is not subject to any technical standard, because it is a natural material. For loam plaster, pay attention to the composition: Loam with a high clay content is called "fat", whereas clay-poor clay is "lean". The clay plaster disadvantages are of course closely related to the ingredients.

Sensitivity to water

Clay is a moisture-sensitive material and should always be protected from rain and splashing water. If a clay plaster is permanently moistened, it loses its stability and begins to weather. Protect your plaster against rain and rising damp! If necessary, set up horizontal barriers and provide suitable outdoor rain protection. By absorbing and releasing water vapor, the volume of clay plaster changes: Therefore, the building material should only be provided with coatings that are elastic enough not to break. A short-term water vapor absorption can also be used positively to keep damp areas mold-free.

Dwindling of fresh clay plaster

Fresh clay plaster shrinks after application by up to 7%, as the water contained in it gradually evaporates. This process can lead to unsightly drying cracks. A clay plaster should therefore always dry as slowly and gently - an artificial acceleration of the process causes unsightly damage. If a part of the mixing water is replaced by other liquefying agents, such as soda, this reduces the loss of material. The addition of river sand also causes the clay plaster to shrink less. Coat your plaster with a coat of paint only after complete drying!

Sensitivity to frost

Another important clay plaster disadvantage is the relatively high frost sensitivity of the material. If there is a certain amount of water in the clay and this water freezes, then the result is frostbite. That is why wet clay should be applied outdoors only in the months of April to September - this of course also applies to indoor areas in the unheated raw state.

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