Stucco is a durable and attractive exterior finish for homes and buildings. It consists of Portland cement, sand, water, and often lime. Stucco is applied wet and hardens to form a stone-like surface. One important step when installing stucco is applying the color coat.
What is a Color Coat?
A color coat, also called a finish coat or pigmented coat, is the final layer of stucco that provides color and protection. The color coat consists of cement, sand, water, and pigments or dyes that add color. The pigments are typically inorganic mineral oxides that provide long-lasting colorfastness. Some common pigments used in stucco color coats include:
- Iron oxides – for red, brown, yellow, and earth tone colors
- Chromium oxides – for green hues
- Titanium dioxide – for white and pastel tints
- Carbon black – for grays
The color coat layer is applied after the brown coat layer in a multi-layer stucco job. The brown coat provides the base layer and structure. The color coat is a thin, decorative layer that adds aesthetic appeal.
Benefits of a Color Coat
There are several benefits to applying a color coat as the finish layer for stucco:
- Aesthetics – The color coat allows the exterior of the building to be finished in almost any hue. This adds great design flexibility.
- Protection – The color coat protects the stucco from water, sun damage, and staining. The pigments help shield against ultraviolet rays.
- Durability – Quality color coats last for decades without fading or peeling. The mineral pigments are very stable.
- Lower maintenance – The color coat minimizes the need for repainting or restaining the exterior over time.
Without a color coat, the stucco would be a natural gray concrete color. The color coat transforms the home’s appearance. The color also makes stucco more attractive than unfinished concrete or cinder block construction.
How Thick Should a Color Coat Be?
Color coat thickness should be about 1/16 to 1/8 inch thick. Some key guidelines on application thickness include:
- Use a thickness of 1/16 inch for fine sand float finishes
- Apply 3/32 inch for coarser textured surfaces like Spanish lace
- Up to 1/8 inch can be used for deeply textured trowel finishes
- Increasing the thickness does not improve performance – an excessively thick coat may crack
It is important not to make the color coat too thin. This could lead to issues like:
- Visible undulations in the stucco surface
- Difficulty obtaining complete and uniform coverage
- Reduced durability and weather resistance
A thin coat may also require more finish paint or sealer to properly cover and seal the surface. Using the appropriate thickness for the color coat based on the texture avoids these problems.
Applying the color coat takes skill and care to achieve an attractive finish. Here is an overview of the application process:
- Ensure the brown coat surface is fully cured and properly prepared. Lightly moisten the surface before applying the color coat.
- Mix the color coat material wearing protective gear. Use a paddle mixer on a low speed drill. The mix proportions are typically 1 part cement, 3 to 4 parts sand, pigments, and enough water to achieve a workable consistency.
- Trowel apply a tight, thin coat with overlapping strokes. Press the material firmly into the grooves and textures of the stucco surface.
- Keep a wet edge as you work. Blend sections together before moving on.
- Let the color coat cure undisturbed for 48-72 hours. Mist occasionally with water to prevent premature drying.
- Apply any secondary finishes like paints or sealers after full curing, if desired.
Take precautions like using kneeboards and avoiding downspouts when working on scaffolding. Careful planning of the staging around the building is needed. Having an experienced stucco crew handle the color coat is recommended to get a professional quality finish.
Some tips when selecting a color coat and finish for stucco include:
- Consider the style and surroundings of the building. Complement architectural features.
- Lighter tones can make a building appear larger. Darker shades have the opposite effect.
- Softer colors like grays, taupes, and beiges are versatile and timeless.
- Bright colors work well on accent walls or small areas. Use sparingly.
- View large samples on the wall at different times of day. Colors appear different in morning vs. evening light.
- Coordinate with the roof, trim, entry doors, and other exterior elements.
Also factor in the texture. Finer sand float finishes show off vibrant colors and are easier to cover. Heavily textured stucco can dull hues, and work best with neutral tones. Any variations in the substrate can telegraph through with strong colors.
There are many possible texture alternatives when applying stucco. Here are some of the most popular textures and finishes:
- Almost completely smooth surface
- Resembles concrete or plaster
- Requires a highly skilled plasterer
- Great for modern styles
Sand Float Finish
- Slight sandy texture from fine sand added during floating
- Most common and versatile finish
- Low-cost and easy to achieve
- Works with wide range of styles and colors
- Distinctive patterned depressions
- Created by hand application or texturing tools
- Provides visual interest and shadows
- Variations include Spanish lace, California lace, etc.
- Coarse texture from pea gravel or other aggregate thrown onto the surface
- Provides a rough, rustic look
- Durable and masks surface irregularities
- Moroccan dash has colorful aggregates in the mix
There are limitless ways to personalize the look and texture of stucco. Consult with experienced plasterers to explore the options. Carefully constructed mockups are helpful to visualize the finish.
Like other building materials, stucco needs periodic maintenance to retain its beauty and functionality over decades of service. Key aspects of stucco color coat maintenance include:
- Inspect annually – Look for cracks, damage, and moisture issues. Repair promptly to prevent water infiltration.
- Re-seal as needed – Adding a fresh sealant every 4-5 years helps preserve the finish.
- Clean gently – Use low pressure water and mild cleaners. Avoid abrasives or high pressure washing.
- Watch use of vegetation – Prevent root, vine, or ivy growth from damaging the stucco.
- Check flashings and edges – These are vulnerable points for leaks. Ensure proper seals are maintained.
With proper maintenance and occasional touch-ups, a quality stucco and color coat installation can last for 50 years or longer.
Benefits Compared to Other Claddings
Stucco is one of the most popular exterior building surfaces, along with materials like wood siding, brick, stone veneer, vinyl siding, and fiber cement boards. How does stucco compare to other cladding options?
As the table shows, stucco offers many advantages in terms of durability, weather resistance, fire safety, and low maintenance. The installed cost is also very affordable compared to other cladding materials. Combined with the design flexibility of color coat finishes, stucco is an ideal choice for many homes and commercial buildings.
The color coat is a critical part of any stucco installation. This thin decorative layer provides aesthetics, protection, and longevity. Careful attention should be paid to the color selection, texture, proper application procedures, and maintenance with any stucco and color coat project. With a quality installation and periodic upkeep, a beautiful stucco facade with custom color coat can grace a home or building for decades to come.