» The difference in these types of finishes is the aggregate size for the most part, although every type of finish can be applied a number of ways. The following are considered industry standard finish references; Fine Float, Float, Textured, Machine Applied-Dash, Smooth and Semi-Smooth.

Stucco types and texture descriptions:

16/20 is the coarsest and considered the industry standard finish.
Standard single application Float finish or scratch and double-same day two coat application.
Textured-Skip trowel (Knock Down) is a same day two coat application with a float finish background.
Machine Applied-Dash finish, is a scratch and double-two coat, allowed to dry between applications.

20/30 is considered a high-end residential or commercial level finish.
Fine Float finish, is a scratch and double-same day two coat.
Skip Trowel and Free Style finishes, are same day two coat applications with trowel chatter or float finish background.
Light or Extra Fine Machine Applied-Dash Finish, a scratch and double-two coat, allowed to dry between applications.

Santa Barbara Mission Finish (SBMF) contains only # 30 silica sand.
Smooth, Semi-Smooth, Cat Face, Mission, and Free Style Finishes, are a scratch and double-same day two coat application with trowel chatter or float finish background.

» Acrylic finishes utilize paint technology with aggregates added that can be trowel or spray applied with the appropriate equipment. Acrylic finishes can be applied over portland cement base substrates and EIF Systems using an approved grade.

Stucco Color Coat is a natural cement-based material; acrylic finish is a synthetic man-made coating. Stucco cures to a hardened state while acrylics dry to a hardened state.

Acrylics dry from the outside in and can be sensitive to environmental conditions. Air circulation is as important for drying as the temperature, especially in humid conditions. Cement stucco finish “cures” as opposed to drying.

Cement finish coats are a nominal 1/8 inch thick and have the ability to fill small imperfections in the base coat. Acrylic finishes have very little ability to compensate for surface irregularities.

For acrylics or cement finish, the portland cement plaster base coat must be cured before applying the finish, but a longer cure time is beneficial. It gives the building additional time to “find itself” or settle before the finish coat is applied.

Based on the type of acrylic finish and the texture of the existing surface, a skim coat of Stucco Level Coat may be required, a color matched acrylic primer may be recommended or in some cases color coordinated acrylic primer may be required.

Water Repellency:
Traditional cement Stucco Color Coat, like all cement products, will absorb surface moisture and darken when wet. Acrylics will repel surface moisture, but moisture will pass through as a vapor. Acrylic finishes should never be mistakenly used as a method to “seal” the building from water intrusion. Properly applied Portland cement plaster base coat will keep moisture out while remaining vapor permeable. It is advisable that all finish coat materials, including paint, be a “breathable” membrane.

Acrylic finish should never be used on horizontal surfaces or other areas susceptible to ponding water. An advantage of acrylic finish is that they maintain their color when wet which is a consideration in wet climates.

Flexibility:
Cement based finish coats are not flexible and hairline cracks will often transfer through the finish. Acrylic finish coats are more flexible when initially installed and tend to hide minor hairline cracking in the first year or so. However, acrylic finish coats are not considered an elastomeric. After exposure to the sun, the acrylics tend to harden and hairline cracks may appear at a later time.

Maintenance:
Both Stucco Color Coat and Acrylic finishes are relatively low maintenance and both can be coated with appropriate materials when a change of color is desired. Acrylic finishes have proven to work well over 30 years. Stucco finishes have proven to work well for many decades, well over 75 years in some cases.

Conclusion:
Both Stucco Color Coat and Acrylic finishes have strong points and some limitations. Designers and owners should review a complete list of features to determine which finish is most appropriate.

» The Rain will stain; protect your Stucco Color Coat with a water repellent. Pro-Tect water repellent is effective at repelling stains due to water born material on Stucco Color Coat finishes that are in acceptable condition, helping protect wall against water saturation. Wait until fresh Stucco Color Coat has cured before applying a Pro-Tect water repellent.

Truly sealing Stucco Color Coat is not the best option, be sure to use a “breathable” material.

» Yes Stucco Plus will sandblast and re-stucco your residential or commercial property.

» A certain amount of cracking in stucco basecoats (which has simply transferred through the finish) is normal. Certain fine or smooth textures accentuate cracks in stucco, while heavier textures tend to hide stucco cracks. Although not all cracks are objectionable, cracks in stucco acceptable to one person might be unacceptable to another person.

Cracks can appear in stucco regardless of texture. Building codes and ASTM C926 do not call for a required hardness (PSI) for Portland Cement Plaster. Minor cracking at the corners of doors and windows and other stress points is reasonable and should be anticipated, color coat stucco is not structural; it is a decorative finish.

Cracks that appear on the surface of stucco walls are usually caused by conditions within the wall structure. Some of these conditions include shrinkage of wood based (green or wet) framing members, thermal expansion and contraction, ground movement and soil expansion and contraction, shear panel flexing, water intrusion (which can cause wood based framing members and sheathing to swell) and a variety of other jobsite conditions. Plaster does not shift outward of its own volition after it is stabilized, it must be pushed out of alignment by some significant force.

Cracks may also appear in stucco due to shrinkage (hydration, rapid loss of moisture, wind and high temperatures) can cause checking cracking. Freshly applied stucco basecoats should be moisture cured and should be protected against rapid drying from high winds. In extreme conditions moisture curing of the finish with a fine mist of clean water may also be necessary.

Although stucco assemblies do sometimes crack, it does not mean that the stucco has failed or was installed incorrectly, it simply means that stresses from outside sources are present, and have relived themselves in the plaster membrane.

Patching of hairline cracks 1/16″ or less is not recommended as it will detract from the natural beauty of the stucco and will serve no useful purpose. In most cases the repair of them will be more apparent than the crack itself. The patching of larger stucco cracks can be completed with the same finish material and color used for the existing finish.