Expert ADVICE
STUCCO, IN ITS ORIGINAL FORM, IS ONE OF THE MOST WIDELY USED AND MOST TRADITIONAL BUILDING MATERIALS IN THE WORLD.
A Word about Stucco
“Traditional” cementitious stucco is usually applied as a multi-layer process. The first layer, or scratch coat, is applied over expanded metal lath. The second layer is commonly called a brown coat and the final layer is the color or finish coat. The key to a good “traditional” stucco job is the wetting of these materials as they are applied. This helps to prevent the too rapid evaporation of moisture from the scratch and brown coats. Extruded metal lath applied to parapets, windows and splash areas in preparation for a traditional stucco application Inset: Extruded metal lath over window flashing in preparation for traditional stucco application..
Ricardo Chavez Klaus Herring Co-owners
ARCS Alpha Restoration & Construction Services, Inc. 505.473.2057 6820 Cerrillos Road #8 Klaus.H@ARCS247.com www.ARCS247.com
Taos Pueblo, a UNESCO World Heritage site, is a stunning example of Native American architecture utilizing traditional adobe stucco.
“At Harlicanassus, the house of that most potent king Mausolus, though decorated throughout with Proconnesian marble, has walls built of brick which are to this day of extraordinary strength, and are covered with stucco so highly polished that they seem to be as glistening glass…” —Marcus Vitruvius Pollio (80 BC to 15 BC) Roman author, architect, civil and military engineer speaking about the residence of the Greek King Mausolus
N
ow that spring is officially here, many of you are looking at those unsightly cracks in your stucco, those spalling freeze damaged parapets, and the white, chalky mineral deposits around the bottom of the stucco, and you’re considering perhaps re-doing those walls. Before you do, you should know a little bit about stucco. Stucco, in its original form, is one of the most widely used and most traditional building materials in the world. Some say that the ancient pyramids in Egypt were covered in stucco, even before the Greeks and Romans started using it. Historians have been able to date stucco back to Mesopotamia (now modern day Iraq). In its original form, stucco
is made from hydrated lime and sand mixed together. In time, this mixture was amended with natural cement (powdered limestone and clay). Great examples of early stucco applications can be found on the great adobe buildings of the Native American Pueblos right here in New Mexico, most notable among them are the multi-story dwellings of Taos Pueblo. When originally constructed, these adobe buildings had an exterior coating of adobe mud with straw additives. To this day, they are maintained by the tribe in the traditional manner. Taos Pueblo is not only a National Historic Landmark but also a UNESCO World Heritage Site and worth a visit for anyone interested in pre-Hispanic Native American architecture.
Since then, cementitious stucco is made up of Portland cement, sand and water with some manufacturers still adding lime. This is the “traditional” stucco you see on most of the buildings in Santa Fe’s historic districts. There are some buildings which still have the ancient lime formulation on some of their walls. An example of this are the white-colored walls in the courtyard and rear of the Palace of the Governors, on the Plaza in Santa Fe.
It was not until the ‘80s that stucco experienced its second revolution. This is when stucco morphed into EIFS (Elastomeric Insulated Finish Systems). Many argue that these modern systems are not stucco at all, but most Americans now recognize these systems as “stucco.” These products are marketed, sold and warranted as a “system,” and need to be applied by certified installers. There are a number of brands selling elastomeric and acrylic stucco products in a wide variety of colors and finishes.
In its early days, stucco was also called plaster and there was no differentiation between the two. Michelangelo used plaster to create the famous frescos in the Sistine Chapel of the Vatican. It was not until 1824, when Joseph Aspdin, a brick layer from Leeds, England invented Portland cement that the composition of stucco changed. Portland cement was added to the mixture in order to keep stucco strong, which revolutionized the coating. Portland cement was not manufactured in the United States until the 1870s. This version of stucco became prevalent throughout the United States after 1890 and became all the rage in the 1930s and 1940s when it was associated with building styles like Prairie, Art Deco, Art Moderne, Spanish Colonial, Mission, Pueblo, Mediterranean and others.
All of this take considerable time and craftsmanship. Normally, depending on weather conditions and humidity (or lack thereof), it usually takes 24 to 72 hours for each coat to dry. Drying too fast results in cracking, loss of bond and generally poor quality work. Often, depending on the time of year, the gray cementitious surfaces are left to sit and cure. Normal timeframes for good stucco installations start after the last frost in the spring, with overnight temperatures consistently in the 40s. This installation window closes when the first frost hits in the fall and overnight temperatures dip below the 40-degree mark. Synthetic stucco products are usually applied over a variety of manufacturerapproved substrates, which often includes a cementitious base coat which is then covered by a finish coat that contains elastomeric or acrylic formulations. If these types of systems are considered for your home, make sure you educate yourself about the product and the manufacturers required installation procedures. Insist that your certified installer follows these procedures. If these coatings are applied by a non-certified installer who does not follow manufacturers written procedures, you will not have a warranty on your installation and thus no recourse should the system fail on your home. To schedule a free consultation for your stucco installation call ARCS at 505.473.2057.
Installation of modern synthetic stucco system over existing stucco application. Inset: Fiberglass mesh embedded into base coat prior to installation of synthetic finish coat.