Since centuries, stucco has been used to decorate and protect exterior and interior ceilings and walls. Stucco comes in many textures and thousands of colors. It is the preferred cladding for new construction, remodels, and restoration projects.
There are two main types of exterior stucco, Hard Coat Stucco and EIFS, which can be used in dozens of ways. Hard Coat Stucco is preferred for multifamily or residential construction and is increasingly being used for commercial projects because it is less expensive. EIFS is most commonly used in commercial building projects but it is also often used for custom high-end homes.
Hard Coat Stucco can be applied in two to three coats and has a cementitious foundation coat. One Coat Stucco is one of the most popular hard coat stucco systems. Three Coat Stucco is another. Three Coat Stucco is a traditional three-coat system that consists of two coats, one cement base coat and one final coat. One Coat Stucco can be described as a two-coat process, but it does not require two base coats. Instead, one cementitious coat is applied with one final coat. One Coat Stucco is becoming more popular over the past few decades due to its low cost. Both systems use the same materials and process of application, with the exception that One Coat Stucco takes less time and requires fewer steps. Although the performance and design abilities of both systems are the same, Three Coat Stucco tends to be stronger and cracks less under most circumstances.
Both hard coat systems can be applied the same way. Although there are many options for finishing, they can all be combined into three categories: Acrylic Finishes, Painted Stucco and Integrally Colored Stucco. For most of the 20th Century, colored cement finishes (or “colored stucco”) were the preferred choice over Three Coat Stucco. It is simply a mixture cement, lime, sand, and pigment. It’s inexpensive and easy to use, but if the base coat cracks, the finish will almost certainly crack. Colored Stucco is easy to stain, can be difficult to repair and allows water to flow freely through it. This can either be good or bad, depending on where the system is being used. It can be applied by hand and can achieve almost any finish.
The majority of finishes used today are painted stucco. It has been around for almost as long. Painted Stucco uses the same materials, but the color is less. It is applied in the same way and can achieve the same textures as integrally colored stucco. The last step in Painted Stucco’s process is the application of paint. Paint, also known as “coating”, is more vibrant and easier to apply. There are many color options, so it is important to use a high-quality stucco paint. Acrylic Stucco, or Acrylic Finish is the most popular stucco finish. This system is sometimes called Synthetic Stucco. However, it is not a synthetic one.
Acrylic Finish can be applied in many colors just like paint. It has the same chemical makeup as paint but is thicker. Although this does increase the overall cost, it offers many advantages that the other finishes do not. Acrylic Stucco can bridge most hairline cracks. It also prevents water from traveling freely through the system. This is an important benefit for freeze/thaw zones. Acrylic Stucco will look great for many years and will not need any maintenance. Painting stucco will require a lot of work and must be repainted every few years. Colored stucco stains easily and will show every crack. It is extremely difficult to repair.
EIFS stands for full synthetic systems or Synthetic Stucco. EIFS systems are lighter than traditional stucco, and more flexible. EIFS adhesives, and base coats, are primarily cement-based. However, they have been heavily modified with polymers so that they can be considered synthetic. While these systems have been in use for decades, they are relatively new to the stucco industry. EIFS systems almost all use EPS (Expanded Polystyrene), an insulation board that is often attached to the substrate by adhesive or mechanically. EPS is an insulation that adds to the wall assembly and absorbs movement better then any other stucco cladding. It also offers many design options.
Original or traditional EIFS systems used a cement-based adhesive,/or mechanical fasteners, for the EPS, fiberglass netting for reinforcement, to gauge basecoat thickness, cement basecoat, and an acrylic finishing. These systems are called Barrier EIFS. These systems are watertight and can’t allow water to escape. Before these problems became a problem, the industry developed Drainage EIFS (or Water Managed EIFS) that some manufacturers had promoted. Drainage EIFS systems are very popular and can include additional or modified components like notched or channeled EIFS, plastic trim, trowel-applied waterproof coatings, or trowel-applied EPS. These systems appear to have solved the water drainage problem that existed in years past. EIFS has fewer options for finishing coats than Hard Coat Stucco. EIFS is a soft system or synthetic system. This means that cement finishes won’t work unless they have been acrylic or polymer modified.
EIFS manufacturers follow their recommendations and won’t warranty products that are not in line with the original specifications. Nearly every EIFS final coat consists of an acrylic oil and a marble or silica-sand finish, which is then hand-troweled on top of the base coat. Acrylic finishes are very flexible and integrally colored. Acrylic finishes come in a variety of textures, including a smooth finish, sand finish, and rilled or swirly finish. These expensive finishes are typically applied in one coat with a thickness of 5/32″. Multilayering acrylic finishes can create many textures.