Repairing Stucco Finish Walls: Synthetic Stucco Can Give Old Stucco Walls A Brand New Look

(HIT) - Stucco has a lot of advantages as a home exterior. It is durable, fire-resistant, able to withstand harsh climates and, of course, it looks great. However, the traditional stucco mixture of cement, sand, lime and water does have its faults.

Most notably, traditional stucco is susceptible to cracking when exposed to normal building movement due to thermal expansion and contraction. Small cracks in stucco exteriors can usually be repaired using a stucco patch material. Extensive deterioration, however, presents more of a challenge.

The problem lies in the fact that it’s very difficult to match the exact color and texture of existing stucco with any kind of stucco patch material, thus repairing major cracks or holes will often create an undesirable "patchwork" appearance.

Repairing Stucco Walls With Synthetic Stucco

The good news for homeowners is that engineering advances have resulted in the development of synthetic stucco materials, which offer improved flexibility for superior crack resistance. Because synthetic stucco is acrylic-based, instead of just rigid cement, it is able to accommodate normal building movement much better than conventional stucco.

Even better news for homeowners with cement-based stucco exteriors in need of repair is the fact that USG Corporation offers its synthetic stucco for use as a finish material over deteriorating conventional stucco. By applying a thin layer of synthetic stucco, base coat, mesh and finish over existing stucco walls, you not only hide cracks and other deterioration, but you can also improve the exterior's resistance to cracking for years to come.

Synthetic finishes, such as USG Exterior Textured Finish, are also easier to apply than conventional stucco. They come in a choice of textures—fine, medium and coarse—and a full range of colors.

Repairing Conventional Stucco

If stucco cracking is minor, cement-based stucco can be patched using either conventional stucco patch material or a polymer basecoat product. First, thoroughly clean all dirt and loose cement from the crack or hole, then fill the area with patch material, troweling it to match the texture of the existing surface. Since it is difficult to match colors and textures exactly, these kinds of repairs should be limited to only very small areas.

To recoat an existing stucco wall with synthetic stucco, first clean the existing surface. All dirt and loose materials should be removed and paint or other coatings should be waterblasted. Fill any small voids or depressions using a polymer-modified portland cement basecoat material, such as USG Exterior Basecoat. Large holes, greater than 1/4" deep, should be filled with a conventional portland cement brown coat stucco mix.

Next, apply a layer of basecoat over the entire wall surface. Tightly scratch the material into the existing stucco surface. Embed a reinforcing mesh into the basecoat layer and immediately apply a second layer of basecoat, completely embedding the mesh. The mesh should not be visible through the second layer of basecoat.

Allow the basecoat layer to cure a minimum of 24 hours and then apply the synthetic stucco finish to a minimum 1/16" thickness. Float or trowel it to the desired texture.

The beauty of USG’s synthetic stucco system is that the reinforced basecoat layer reduces the potential for existing cracks to affect the finished synthetic stucco surface, while the flexibility of the finish minimizes the chances for new cracks to develop. The result is a comparatively economical wall that looks better and will last longer.

Material costs for using the synthetic stucco finish, basecoat and mesh vary significantly depending on application but typically range from $1.50 to $3.00 per square foot of coverage. Application costs vary depending on the contractor you select and job conditions.

To obtain more information about stucco repair and synthetic stucco overcoat options, visit USG online at www.usg.com.

Courtesy: Home Improvement News and Information Center