The Art and Architecture of Stucco

Stucco Definitions and Uses

Stucco Sided Dwellings in Ybbsitz, Lower Autria
Stucco Sided Dwellings in Ybbsitz, Lower Autria. Photo by Imagno / Hulton Archive / Getty Images (crop)

Stucco is a mortar mixture that is commonly used as an exterior siding application on houses. Historically it has been used as a sculpting medium for architectural ornamentation. Stucco can be made by mixing sand and lime with water and various other ingredients, most often cement. Like frosting on a cracked layer cake, a good layer of stucco can enrich a once-shabby exterior.

The plaster-like material, however, has many decorative uses and is found throughout the world.

For centuries stucco has been used not only in Middle Eastern mosques, but also as ornate Rococo ornamentation in Bavarian pilgrimage churches.

The Stucco Wall

Stucco is more than a thin veneer but it is not a building material—a "stucco wall" is not structurally made of stucco. Stucco is the finish applied to the wall.

Usually, wooden walls are covered with tar paper and chicken wire or galvanized metal screening called casing bead. Interior walls may have wooden laths. This framework is then covered with layers of stucco mixture. The first layer is called a scratch coat, and then a brown coat is applied to the dried scratch coat. The tinted finish coat is the surface everyone sees.

For masonry walls, including damaged brick and concrete block that a homeowner wishes to hide, preparation is easier. A bonding agent is usually brushed on, and then the stucco mixture is applied directly to the power-washed and prepared masonry surface.

How to repair stucco? Historic preservationists have written extensively on the topic in Preservation Brief 22.

Definitions

Stucco is often defined by both how it is made and where (and how) it is applied.

Historic preservationists in Great Britain describe a common stucco as a combination of lime, sand and hair—with the hair "long, strong, and free of dirt and grease, from the horse or ox." A 1976 Time-Life home repair book describes stucco as "mortar containing hydrated lime and asbestos"—probably not a recommended additive today.

The 1980 Penguin Dictionary of Architecture simply describes stucco as "Plasterwork usually rendered very smooth or modelled as in stucco ceilings." The Dictionary of Architecture and Construction covers all bases:

stucco 1. An exterior finish, usually textured; composed of portland cement, lime, and sand, which are mixed with water. 2. A fine plaster used for decorative work or moldings. 3. Simulated stucco containing other materials, such as epoxy as a binder. 4. A partially or fully calcined gypsum that has not yet been processed into a finished product.

Decorative Stucco

Although stucco-sided homes became popular in twentieth century America, the concept of using stucco mixtures in architecture goes back to ancient times. Wall frescoes by ancient Greeks and Romans were painted on fine-grained hard plaster surfaces made of gypsum, marble dust, and glue.

This marble dust compound could be molded into decorative shapes, polished to a sheen, or painted. Artists like Giacomo Serpotta became stucco masters, incorporating figures into the architecture, like the male nude sitting on a window cornice in the Oratory of the Rosary in Saint Lorenzo in Sicily, Italy.

Stucco techniques were elaborated by the Italians during the Renaissance and the artistry spread throughout Europe.

German craftsmen like Dominikus Zimmermann took stucco designs to new artistic levels with elaborate church interiors, such as The Wieskirche in Bavaria. The exterior of this pilgrimage church is truly Zimmermann's Deception. The simplicity of the walls on the outside belie the extravagant interior ornamentation.

About Synthetic Stucco

Many homes built after the 1950s use a variety of synthetic materials that resemble stucco. Mock stucco siding is often composed of foam insulation board or cement panels secured to the walls. Although synthetic stucco may look authentic, real stucco tends to be heavier. Walls made of genuine stucco sound solid when tapped and will be less likely to suffer damage from a hard blow. Also, genuine stucco holds up well in wet conditions. Although it is porous and will absorb moisture, genuine stucco will dry easily, without damage to the structure—especially when installed with weep screeds.

One type of synthetic stucco, known as EIFS (Exterior Insulation and Finish Systems), has long been associated with moisture problems. The underlying wood on EIFS-sided homes tended to suffer rot damage. A simple Web search for "stucco lawsuit" reveals plenty of problems up and down the East coast beginning in the 1990s. "Experts say stucco can be done right, or it can be done quickly," reported Florida's 10NEWS-TV. "And when builders are trying to put homes up as fast - or as cheap - as possible, they often choose the latter. "

Other types of synthetic stucco are quite durable, and the AIA's magazine, Architect, reports that building codes and commercial products have changed in the past few years. It's always a wise to have a professional inspection before purchasing a stucco-sided home.

Examples of Use

Stucco siding is most often found on Mission Revival style and Spanish and Mediterranean style homes.

When traveling to southern US environs, notice that concrete block is often used for sturdy, wind-resistant, energy-efficient homes and public buildings like schools and town halls. Many times these blocks are finished with only a hearty paint, but a coating of stucco is said to increase the value (and status) of these concrete block homes. There's even an abbreviation for the practice—CBS for "concrete block and stucco."

When visiting the Art Deco buildings throughout Miami Beach, Florida, note that most are stucco over block. We've been told that developers who insist on a stucco finish on wood frame structures end up having a heap of moisture problems.

Stephen Walker wrote to us about his problematic stucco:

we have a straw bale home 100 miles s of San Antonio, Tx. It is very hot, humid, cold, very hot, windy with some downpours. The portland stucco finish is badly cracked and chipping. Inside, the stucco is ok with some small cracks. The house is 10 yrs old. We were told to seek out a "stucco restoration specialist". Your article was very interesting. Can you help us?

Not all stucco problems are the same. A wall made of straw bale will have different needs than concrete block or timber frame construction. Consulting a "stucco restoration specialist" who may know nothing about straw bale construction might be a mistake. Stucco recipes are not "one size fits all." Mixtures are many.

Having said all that, you can buy premixed and preformulated stucco. Both DAP and Quikrete sell bags and buckets of the mixture at big box stores and even on Amazon.com. Other companies, such as Liquitex, supply stucco mixtures for artists.

Learn More

Sources

  • Exterior Stucco by Ian Constantinides and Lynne Humphries, The Building Conservation Directory, 2003 at buildingconservation.com [accessed February 12, 2016]
  • Time-Life books, Home Repair and Improvement, 1976, Masonry, Index/Glossary, p. 127
  • The Penguin Dictionary of Architecture, John Fleming, Hugh Honour, Midolaus Pevner, 3rd edition, 1980, p. 313
  • Dictionary of Architecture and Construction, Cyril M. Harris, ed., McGraw- Hill, 1975, pp. 482-483