Stucco

Until the latter part of the nineteenth century, it was common that mortar as well as plaster, which was used inside a building, and stucco, which was used outside, would consist of the same primary materials: lime and sand.

It was traditionally used as both an interior and exterior finish applied in one or two thin layers directly over a solid masonry, brick, or stone surface.

Then with the introduction and development of heavy timber and light wood-framed construction methods, stucco was adapted for this new use by adding a reinforcement lattice, or lath, attached to and spanning between the structural supports and by increasing the thickness and number of layers of the total system.

The lath added support for the wet plaster and tensile strength to the brittle, cured stucco; while the increased thickness and number of layers helped control cracking.

Originally, the lath material was strips of wood installed horizontally on the wall, with spaces between, that would support the wet plaster until it cured.

In exterior wall applications, the lath is installed over a weather-resistant asphalt-impregnated felt or paper sheet that protects the framing from the moisture that can pass through the porous stucco.

In some parts of the United States with a warmer climate (like California, Nevada, Arizona, New Mexico and Florida), stucco is the predominant exterior for both residential and commercial construction.

Stucco exterior (with wood frame interior) became a popular alternative in the southwestern United States during the 1970s, as the masonry labor costs for adobe rose.

The Greco-Buddhist art of modern Afghanistan and northern Pakistan made extensive use in monasteries and temples of stucco for three-dimensional monumental sculpture as well as reliefs.

Since stucco can be used for decoration as well as for figurative representation, it provides an ideal transitive link from architectural details to wall paintings such as the typically Baroque trompe-l'œil ceilings, as in the work of the Wessobrunner School.

Plastic or wire mesh lath, attached with nails or screws to the structural framing, is embedded into the base coat to provide stiffening for the stucco.

Where stucco is to be applied to a structure of wood-framing or light-gauge steel framing, the framing is protected from moisture damage by applying a cement based primer, or a vapor-permeable, water-resistant weather barrier; typically an asphalt-saturated paper or one of a variety of manufactured plastic-based sheets, known as "building wraps" or "stucco wraps".

The properties of the weather barrier must not only protect the framing from rain and moisture, but at the same time allow the free passage of any water vapor generated inside the building to escape through the wall.

A wide variety of stucco accessories, such as weep screeds, control and expansion joints, corner-aids and architectural reveals are sometimes also incorporated into the lath.