In ancient times, builders and architects didn’t perform extensive field trials of their designs and materials. Nevertheless, many of their structures survived for centuries — partly because they used durable materials such as stucco. This popular exterior surface treatment was inspired by an interior finish known for its decorative appeal and durability: plaster. Thought to originate in Italy, the technique spread as builders applied similar materials to masonry and wood exteriors throughout Europe and the Middle East. In the early 19th century, British architects such as John Nash helped the stucco trend to move westward by specifying the material for many of their buildings.
Sometimes called “poor man’s stone,” stucco was cheap and readily available. Used as a façade where stone was not naturally plentiful, stucco could be applied and scored to imitate masonry joints and fine stone on structures of any shape and size.
In many ways, exterior stucco was an early form of composite siding (without the measuring and cutting). Originally made of lime, crushed marble, sand and various binders, the finish’s recipe has changed depending on available ingredients. The list of occasional additives reads like a chemistry experiment mixed with a recipe for down-home cooking: hair, blood and urine from animals, glue size (from hooves and horns), straw, sawdust, eggs, sugar, salt, alum, linseed oil, wine, beer, whiskey, waxes and varnishes.
Traditionally a coating of many colors, stucco’s appearance varied according to the tint of the sand it contained or supplementary mineral pigments. During the last century, manufactured stucco mixes have included synthetic pigments to create vibrant colors. The finish’s texture and appearance also change with variations in the coarseness of ingredients and differing application methods. (Remember the popular straw-and-stucco decor of the 1970s?)
Stucco is not merely decorative, however; it envelopes structures to shield them from the elements, and the hardened surface helps to enhance structural strength. Although it will absorb some moisture, stucco’s permeability allows it to drain and dry. The original lime-base stucco is somewhat flexible and porous; the harder cement-base stucco that became popular around the beginning of the 20th century is also porous but less flexible. Because lime-base stucco and cement-base stucco are incompatible, it’s important to know which kind you’re working with when making a repair. And like most manmade materials, both require maintenance to prevent decay.
Stucco helps to distinguish the character of a diverse array of architectural styles. A modest Pueblo-style hut, an art deco Hollywood mansion, an English Tudor cottage, an Italian villa and the bungalow next door may appeal to vastly different tastes, but all of these designs share a common trait: their tough, classically beautiful stucco skins.
Though many people use the terms concrete and cement (a main ingredient in stucco) interchangeably, they are as different as ice cream and a malted milkshake. Like a shake, concrete is a concoction of various ingredients, one of which is cement. Cement (like ice cream) is made through a separate process and combination of ingredients. (Anybody ready for a sundae?)