Gypsum plaster on loam

When loam plaster has to be repaired, many builders come up with the idea to repair with gypsum plaster. Large-scale plastering of plaster on clay does not make the client happy for long, because both substances are incompatible. Damage is inevitable.

Plaster and clay are not a good team

In the renovation of an old property with damaged clay plaster walls, it is close to the easy to use and inexpensive gypsum plaster to grab. Both types of plaster are so-called shell formers. But if they are cleaned over a large area, they can peel off from each other over time. Both substances diffuse moisture, but the clay leaves more moisture in the interior than the plaster. Too much moisture does not tolerate gypsum and swells up.

In general, experts advise against applying gypsum plaster to a clay plaster. If a clay plaster wall disappears, the clay plaster must be completely removed. Only then can another material, such as gypsum plaster, be processed and a durable, perfectly crafted result can be achieved. Repairs to the clay plaster should only be made with clay. This will help you avoid later damage that may be caused by incompatibility of different materials.

Use gypsum plaster only occasionally

If electrical installations have to be made in clay-plastered walls, the electrician prefers to use gypsum plaster. He can quickly plaster cans and lay cables under plaster. Unproblematic is the economical use of gypsum plaster, if it disappears under the can, for example, and only serves for selective attachment. To be on the safe side, the electrician can use a special reinforcing lime mortar, which is very compatible with loam plaster. This mortar binds off as quickly as gypsum plaster and is just as easy to work with.

Tips & Tricks

Clay plaster has been used in home construction for several hundred years. In the framework it also harmonizes well with the wooden beams. To use gypsum plaster here would be fatal. The gypsum plaster would remove moisture from the wood. Damage in gypsum plaster and mold formation are then possible.

Product Image: Dietrich Leppert / Shutterstock

Video Board: Buckland plastering.