The Many Faces and Longevity of Stucco
Putting On A New Coat
Stucco is valued as a siding material for its attractiveness and durability and is a relatively low-maintenance exterior finish. Stucco is often selected for multi-family projects due to the fact that when it is applied to 7/8 inch nominal thickness, provides a one-hour fire rating. It is often used on (but is certainly not limited to) Spanish-style homes. Stucco can be directly applied to brick and concrete primer, or applied over a wood frame, metal siding, or any other material.
While nothing prevents anyone from painting or whitewashing concrete to make it look like stucco, paint generally does not adhere to concrete longer than two or three years, requiring constant re-application. Removing these materials in order to re-stucco requires expensive sandblasting. Paint also prevents the concrete from breathing. A stucco home can be refinished with an integral color stucco which does not require painting. Color can also be added to concrete when it is originally placed before curing, and thus the concrete would not require painting.
Durable, versatile and relatively maintenance free, stucco is an underappreciated way to add a textured charm to your home.
Stucco, a cement plaster that adds charm and curb appeal to exteriors, not only masks minor imperfections, it's also a versatile decorative surface.
It can be tinted or shaped into textures -- smooth or stippled, marbled or spattered. It can be applied as smooth as glass, scored to look like stone or troweled in fanciful patterns such as seashells.
You can dab small mounds with a round-nose trowel for an English cottage feel. Or compliment a Japanese rock garden with a product called Wara Juraku. For more than a century, the Japanese have adorned the walls of teahouses and homes with this plaster composed of straw, clay and sand. It's available in the United States in shades of beige, olive, black or rust.
But stucco offers more than aesthetic appeal. It's fireproof, durable and weather-resistant. Unaffected by dry rot, termites and fungus, it never needs protective paint or sealers. And it requires only minimal care.
Traditional stucco is a blend of portland cement, hydrated lime, sand and water. But in the last 30 years, a more expensive synthetic stucco made of acrylic resins has gained in popularity. It's insulated and multilayered, with a water-resistant base coat that is reinforced with steel mesh, and a synthetic finish coat.
This treatment, Exterior Insulation and Finish Systems or EIFS, forms a protective, weatherproof barrier known for energy efficiency, crack resistance and design versatility. Skilled applicators use computers to create intricate architectural details such as cornices, arches, columns, keystones, cornerstones and moldings.
When most homeowners think of siding, they may think of vinyl, fiber-cement, or plywood. But there is one type of "siding" that has been around for centuries that lets you avoid the problem of dealing with pesky vinyl siding salesmen. It's stucco finish, and unlike other types of house finishes, it applies equally well over masonry and wood-sheathed homes.
The Layers of Stucco: Over Wood or Masonry
The natural place to install a stucco finish is over concrete masonry. Concrete masonry is stable and less prone to expansion and contraction and other movement that may crack the stucco. While stucco finish can be applied to a wood-sheathed home, additional reinforcement is needed.
On concrete masonry, little other than a scratch coat is needed below the stucco finish. A scratch coat is a base layer of cementitious material that is literally scratched horizontally with a comb-like tool.
Wood-sheathed buildings are a different matter. Wood sheathing itself will not provide a proper base for stucco finish. So you need to layer it with Tyvek or other waterproof building paper, and then self-furring metal lath. This lath provides the grip for the scratch coat to hang onto. After the scratch coat, apply a brown coat to provide a smooth surface for the subsequent stucco finish.
What is a fog coat?
A fog coat is a light application of a cement-based slurry, the same proportions of cement, lime (if any), and water as used in the original application minus the sand, used to even out a surface’s appearance. It is typically sprayed or rolled onto the surface, similar to painting with a cement-based paint. Fog coating improves the look of stucco without changing its ability to transmit moisture vapor.