Stucco has a long history as a building material, used extensively throughout the western world and the Middle East for exterior and interior wall construction. It was also used for decoration in both homes and great buildings such as cathedrals and mosques. Basically a mix of an aggregate (mainly sand), a binder such as lime or cement, and water, it can be smooth or textured and makes a weather-resistant, durable surface.
The original mix of lime, sand, and water has given way to ones that use cement as the main binder. Lime is still used as an additive, as it allows the covering to ‘breathe’ and helps seal small cracks. Newer forms may incorporate acrylics or glass fibers for added flexibility and durability. This surfacing may be applied directly over cinder block or brick and also used over wood frame for attractive and low maintenance exteriors. Inside, it can be painted or covered with wallpaper or used alone if an integral color is added to the mix at the factory.
To make stucco cling to underlying wood frame construction, lath made of wood or a metal mesh is attached to the exterior before the base coat is applied. The material, which goes on wet, will bind to the supporting structure as the first coat. Wooden framing is protected by asphalt treated felt or paper, which shields the wood from the moisture of the uncured plastering. house building materials
The three-step process includes the first coat, followed after a drying period by a second coat called the ‘brown layer’, which provides a smooth surface for the final finish. This additional layer will also need to cure slowly for a period of a week or more, not being allowed to dry too quickly at first. The process of drying, or curing, goes on until all shrinking and the resultant cracking is done.
The final coat is then applied. Many of the finishes have the color integrated at the factory, which means that there is no need for painting either at the time of installation or in the future. If desired, the stucco may be painted with a cement-based formula, which does not interfere with the vapor permeability of the stucco. It is important for both the stucco and the interior of the house that the finish not be a complete seal that will trap moisture in the construction materials.
As the surface dries, it becomes hard and brittle. Acrylic added to the mix makes the covering less likely to chip and crack. The siding can have an ‘old world’ look, being very smooth, or can be ‘floated’ to allow the sand to show on the surface. It can also be sanded for an extra slick surface or troweled for the swirls and stippling often seen on interior ceilings or home exteriors.