For thousands of years stuccoing has been the most widely used method of finishing building exteriors throughout the world. It is a mortar-like mixture of lime and/or portland cement plus sand, water and often fiberglass or other fibers for strength and stability.
Stucco is applied in thin layers directly onto masonry walls, or troweled over a metal reinforcement attached to wall studs when the walls are wood frame. It is important that the stucco does not dry too quickly so that it can achieve its full strength. Therefore it is usually damp-cured, which means it is sprayed with water at frequent intervals during the curing process. This process takes several days. Skilled craftsmen can apply many different kinds of decorative finishes to the still-wet stucco to enhance its appearance. The final layer is usually an acrylic coating to which color has been added. This coating is washable and will help retain the beauty of the stucco for years to come.
Sometimes what appears to be stucco on a home is actually an Exterior Insulation and Finish System (EIFS), more commonly called synthetic stucco. This popular multi-layered system consists of 1) an insulation layer of expanded polystyrene or polyisocyanurate which is affixed to the exterior wall surface, 2) a secondary moisture barrier to protect the substrate underneath the EIFS, 3) a mesh-reinforced base coat and 4) a finish coat made with 100% acrylic polymers to resist fading and UV degradation. An additional layer that drains away any moisture that should find its way behind the EIFS is especially useful in wet climates.
One advantage of the EIFS is that it envelopes the home with an unbroken layer of insulation, greatly reducing heating and cooling costs. It does not need to be painted and is dirt and mildew resistant. Even more exciting is the fact that the EIFS allows designers to create interesting facades with graceful columns and balustrades, soft curves and arches as well as other architectural shapes which would be cost prohibitive using other materials.