Stucco House Finish: Basics, Application, Pros, and Cons

Stucco is an exterior home finishing plaster coat found on homes nationwide, due to its durability and versatility. Though fiber-cement panels, vinyl siding, and plywood are popular siding materials, stucco has been used for centuries and continues to serve homes well.

House exteriors are composed of many layers that work together. The outermost layer is the most important to the home's lifespan: the siding or cladding. Unlike other forms of siding, stucco applies equally well to masonry and wood-sheathed homes.

What Is Stucco?

Stucco is a cement-type mixture of Portland cement, lime, sand, and water. Its ingredients are mixed and applied wet and then dried to form a durable, hard finish.

Most commonly used on home exteriors, stucco can also be used for interior walls and ceilings as a decorative finish and painted.

It is not necessary to mix stucco with raw ingredients. You can buy pre-mixed stucco finishes at most home centers, which require only the addition of water.

Types of Stucco Finishes

• Sand finish: This popular stucco finish has a grainy, textured look due to the large amount of sand in the mix ratio.
• California finish: Sometimes called a cat face finish, a California stucco finish has a generally smooth surface interspersed with rougher areas.
• Smooth finish: As the name suggests, a smooth stucco finish is smooth, level, and featureless.
• Mission finish: A mission or Santa Barbara stucco finish is left natural and unpainted.

Stucco Application Methods

Stucco is applied using one of three methods: one-coat, two-coat, or three-coat. One-coat methods apply faster. Three-coat methods are the most durable. A three-coat method is best defined by its coats: the scratch coat, brown coat, and finish coat.

• One-coat method: Comprised of Portland cement, sand, fibers, special proprietary chemicals, and water; only requires a single application; can go over rigid foam board and lath
• Two-coat method: Used to coat brick and block walls; requires a bonding adhesive to keep the stucco adhered to the walls; the brown coat is eliminated, and the finish coat is applied directly to the scratch coat
• Three-coat method: Traditional method; can be used over wood sheathing or masonry surfaces; made of cement, sand, fiberglass, acrylic additives, and water; scratch coat starts with an asphalt-infused paper and a rough, scratched layer, next is the base layer or brown coat stucco, then a finish coat for texture and color
  

Pros and Cons of Stucco

Pros

• Easy to customize: Stucco is tinted to add color to ensure colorfastness; it can be painted with ordinary exterior house paint; it can be textured in various ways, lending itself well to creative embellishments.
• Inexpensive: Stucco is considered one of the cheapest types of siding because it does not use expensive materials. Most stucco finishes are created from mixes, but you can also make your finish from raw ingredients.
• Resists moisture and inclement weather well: Stucco house finish provides an excellent seal against rain and snow because it is seamless, unlike nearly every other form of siding. Seams allow water and air into a home. Even seams that appear to be well-sealed may eventually open up.
• Long-lasting: Stucco, when well-maintained, can last for 50 to 100 years.
• Resists fire, mold, rot, and termite infestations: Its composite materials naturally deter fire, rot, mold, and termites from invading the outer structure of a home. However, its rugged texture and porous spaces can provide small spaces for persistent mold to set in.
• Easy to maintain: It has one of the lowest annual maintenance costs compared to other siding materials. Maintenance usually involves inspecting the exterior and filling cracks. Because of its resistance to environmental factors (moisture, mold, insects, rot), it keeps maintenance needs to a minimum.

Cons

• Prone to impact damage: Stucco is fragile and can easily be damaged.
• Not easy to DIY: Stucco installation requires mixing, color matching, and application with a trowel. Initial application and repairs are usually best left to the experts.
• Long curing time: Curing or drying for stucco requires at least 24 to 36 hours for each coat.
• Frequent maintenance: It is easy to maintain but is not maintenance-free. You must inspect it regularly, patch cracks, and hose it down to keep dust and dirt from accumulating.
• Installation cost: Although the materials are cheap, the initial layout for professionally installing a stucco exterior to a house is time-intensive, bringing up the installation costs.

How to Apply Stucco

The steps you need to apply stucco depend on your choice of method—from one to three coats. You eliminate the scratch or brown coat in one- or two-coat installations. In general, the three-coat method includes the following steps:

1. Apply bonding agent or stucco wrap: This layer acts as a stabilizing element for the plaster to adhere properly to wood, metal, or plastic lath.
2. Apply scratch coat (base coat): Using a trowel, apply a 1/4- to 1/2-inch layer of the plaster. It may need up to 36 hours to cure.
3. Apply brown or leveling layer: Once the scratch coat is dry, use a trowel to apply a second layer. It also needs to dry thoroughly before adding the last coat.
4. Apply finish coat: After waiting another 36 hours for the brown layer to dry, apply the finish coat with a trowel, making the texture you want to be visible for the home's exterior.
5. Paint: This step is optional; stucco can be tinted, not requiring paint. Acrylic latex is the better choice if applying paint.
   

Stucco on Masonry Siding

One of the best substrates for stucco is concrete masonry. Concrete masonry is stable and less prone to expansion, contraction, and other movements that may crack the stucco.

On concrete masonry, little more than a scratch coat is needed below the stucco finish. A scratch coat is a base layer of cementitious material scratched horizontally with a comb-like tool.

Stucco on Wood Siding

Wood-sheathed buildings require more preparation for a stucco finish than masonry buildings.

Wood sheathing itself will not provide a good base for a stucco finish. You must layer it with a house wrap or other waterproof building paper and then with 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.

How to Maintain Stucco

The rule of thumb with stucco is to inspect your home's exterior for cracks regularly. Weathering may cause micro-cracks that can grow over time, and direct impacts may make holes.

Stucco is easy to patch. Use paintable acrylic caulk to seal any fissures. Large holes or significant damage are best left to a stucco repair professional.

Point sprinklers and gutter downspouts away from stucco surfaces. Although stucco resists water, it's not impervious if cracks occur. Also, continuously introducing damp conditions combined with organic matter (dirt and plant life) invites mold and fungal growth.

How to Clean Stucco

After repairing cracks, clean the stucco once or twice a year. To remove stains, mix a bleach and water solution. To stubborn stains, mix Borax and dish soap into warm water.

• Preliminarily clean stucco walls with a garden hose sprayer to remove dirt and dust.
• Remove stains or algae, mix one part bleach with four parts cool water.
• For more difficult stains, start with one gallon of warm water in a bucket, then add 1/4-cup Borax and 1 tablespoon of liquid dish soap
• Clean unpainted stucco with CLR (calcium, lime, rust) cleaner.
• Avoid using a power washer on stucco, though a very low-pressure setting may be acceptable for strong stucco.