Stucco is a Portland cement based exterior wall coating. There are different types of stucco systems. Below is a brief description of each.

One Coat System

This is the most widely used system in Arizona and the south west deserts' residential construction since the 1980’s. Typically 1-inch Styrofoam and stucco netting (looks like chicken wire) are attached to the framing. A vapor barrier (water proof paper) is under the Styrofoam. These components are called the lath. Over the lath a 3/8-inch cement base coat is applied. The final step is the texture coat. There are several textures see “Texture Types” for more info.

It is called a one coat system because the texture can be applied as soon as the base coat “sets” (firms up). However, this is not how it is actually done. The texture is usually applied after the base coat has dried.

3-Coat System

This system consists of the lath in this case vapor barrier (waterproof paper) and wire (usually looks like chicken wire). That is attached over the framing. Then a 3/8-inch Portland cement scratch coat is applied. Called this because it is scratched with a rake like tool in preparation for the next coat. The next coat is a 3/8-inch brown coat and finally the texture coat is applied. Overall, it is about 7/8- inch thick. There are waiting periods between coats making it a slower application.

This system is rare in the deserts anymore but because of its thickness it is still used where impact or fire resistance is needed. Before the one coat system came about (late 70's early 80's) it was how stucco was done over framing, so older framed homes are 3-coat. It is still used for construction in certain regions in the southwest where there are more moderate temperatures, such as the California central coast.

CMU Work

CMU stands for Concrete Masonry Unit also called block or cinder block. Over block, stucco is purely decorative. So, the usual application is a thin base coat applied directly to the block and then a texture coat.

EIFS

The acronym is Exterior Insulation Finish System. Sometimes referred to as synthetic stucco. This system is extremely rare in Arizona residential construction. It is mostly used on some commercial buildings.

Typically 1 ½ -inch foam is attached to the building. Then a mixture of acrylic polymer paste and Portland cement is applied as a base coat directly to the foam without any wire (lath). A thin flat fiberglass mesh is embedded into the base coat as well. The thickness of this coat is extremely thin only 1/16th  of an inch or so. Then a colored synthetic texture coat is applied over the base coat. Overall the system is only about an 1/8th of an inch thick.

Stucco System Types