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Stucco Basics

Stucco is a prevalent cladding material in the South and Southwest. Its popularity in these areas is because of the availability of raw materials, like sand; its lower cost; and its impact resistance during storms. However, its uniform look, design flexibility and low cost have generated interest in all areas of the U.S. and Canada.

As stucco gains popularity across the U.S., more contractors are considering expanding their businesses to include stucco installation. A few basic steps must be taken and understood before applying this cladding material.

Stucco Types

Stucco has a reputation for being low-maintenance cladding. Stucco, in most cases, is a blend of portland cement, sand, water, fibers and special chemicals that produce a durable, impact-resistant, colorfast, flexible and cost-effective cladding for the residential and commercial markets.

There are two types of stucco: pre-blended and traditional stucco. When working with pre-blended stucco, a contractor will add water and sand at the jobsite. It comes with a manufacturer’s warranty and is quality controlled. Contractorsusing traditional stucco will mix all ingredients together at the site and may have no exact formula. Fibers and other additives are purchased separately. Usually contractors follow a “recipe” passed down from generations. With traditional stucco, there are no warranties, codes or standards.

Using pre-blended versus traditional stucco is a matter of choice.Larry White, plaster division manager of Western Partitions, Tigard, Ore., has been working with stucco for more than 25 years. “Pre-blended stucco mixes are a vast improvement over traditional stucco because it controls the sand and quantity mixture,” White says. “Eighty percent of the mix is sand, and the better quality of sand you have, the better quality mix you’ll have.”

White stresses pre-blended mixes are controlled and come with warranties, which are two benefits when installing stucco. He also emphasizes the key to any good stucco job is the installation. Any problems with stucco are because of what happens during installation, like openings not being flashed properly and resulting in leaks. No matter what type of cladding is used, installation is key.

Bill Rice, president of Commercial Plastering Inc., Bradenton, Fla., agrees. Rice has been in the stucco industry for more than 40 years and has installed pre-blended stucco since the mid-1980s. “If you install the system correctly, it will perform correctly,” Rice says. “Stucco is the outer skin of the building and if installed improperly, leads to cracking, which allows for water intrusion, which then leads to the failing of the outer wall and waterproofing systems on the house. This can lead to other issues, such as mold.”

Pre-installation

To add stucco installation to your portfolio, apprenticeship training is recommended and available through the Falls Church, Va.-based Association of the Walls and Ceilings Industry; Walpole, Mass.-based Air Barrier Association of America; and other industry organizations, as well as from local trade associations. Local plaster and walls and ceilings chapters are also good places to learn. Distributors often conduct trainings when new products come out or there are updates or changes to products, as well as during times of new code requirements.

“Stucco is a skilled trade,” Rice adds. “It’s no different than being a plumber or electrician. It takes time to learn this.”

The basic tools are not expensive, according to White. You’ll need hammers and nails and the usual hand tools, screw guns and air staples to apply the lath. If you are involved in high production and more competitive bids, then you will want to invest in an array of pumps and spray equipment, which can get more costly. One area to look into is machine technology from manufacturers. Sam McCroskey, field superintendent at J&J Acoustics, San Jose, Calif., says, “A number of contractors start off small with a cement mixer and apply by hand.” He adds the application of all stucco has not changed much during his 27 years in the business, but the approach and products have changed.

Installation Steps

Jesse Zepeda, managing member of Generation Plastering, Pasco, Wash., who has 25 years in the stucco business, says step one is to make sure all metal flashing and window flashing is installed correctly to minimize water penetration.

Next, waterproof the wall area with a fluid-applied air and moisture barrier. Then install metal lath to allow for stucco to adhere more evenly.

Step four is to make sure the stucco is mixed correctly before applying a 3/8-inch scratch coat, which is the initial coat of stucco applied with a trowel and deeply scratched with a scarifier tool to keep the coats from separating. Then, follow the scratch coat with a a 3/8-inch brown coat, which levels out the stucco to create a more even coat on top, as well as adds uniformity to the wall.

White advises to also make sure the stucco is floated. A float is a hand tool preferably made from neoprene or wood with a flat face used for smoothing and finishing the surface of the stucco. Floating is the process of creating a rough surface on the brown coat for the finish coat to adhere to.

As the stucco begins to set and is 80 percent hard, rub the wall surface with the float as it gains density to increase strength. Then give it the last lathing. Seven to 14 days of cure time is needed before the finish is applied. In warmer temperatures it will cure in seven days, and it may take 14 days in the winter and colder, damper climates. The scratch and brown coats will shrink as they dry and if the stucco has not cured long enough, it will crack.

While curing, to protect the stucco from hot, sunny areas, you will want to put a tarp or tent on the wall. For a moister cure, you can mist it with water to slow the drying process. For best results, you want stucco to dry slowly. A pre-blended stucco is generally formulated with additives to slow the shrinkage.

A Versatile Choice

Stucco is suited for all climates. “Any type of home is suited for stucco, and stucco can be used successfully anywhere if installed properly,” Rice says. “Stucco can be made to look any way you like; it’s a very versatile product. It is an art form and beauty is in the eye of each individual.”

White concurs: “Stucco is the only product that can really give you the look you want. It’s limitless in texture, color, design and shape. You can use it for high-end finishes to look like limestone and replicate brick or metal panels.”

“As a stucco contractor, I believe if you install the cladding correctly and apply the correct stucco system, you can apply stucco in just about any area and environment with no problems,” Zepeda says.

John Chamberlin is associate product manager for Atlanta-based Sto Corp., responsible for managing the company’s StoPowerwall Stucco and StoQuik Silver Cement Board Stucco product lines.

 

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