Stucco is a natural material consisting of an aggregate, a binder, and water. It is applied wet and hardens when it dries. For centuries, it has been used as a coating for walls and ceilings and for decoration. Stucco may also be used to cover less usually appealing construction materials such as concrete, cinder block, clay brick and adobe.
Modern day stucco is made of Portland cement and water. Lime is often added to decrease the permeability and increase the workability of modern stucco. Sometimes additives such as acrylics and glass fibres are added to recover the structural properties of the plaster as well as its workability. This usually done with what is considered a “one coat” stucco system. Stucco usually consists of one layer of wire lath and two layers of Portland cement-based plaster. However, cement’s crystalline structure cannot accommodate significant movements in the building structure and is thus prone to cracking. Therefore, an additional acrylic finish on top is often applied – it adds flexibility for surface movements.