Why Use Stucco For My Home?
Stucco has been used in architectural structures since the Greek and Roman era and during the Renaissance. It spread throughout Europe and gradually became popular in America. Stucco is a finishing plaster composed of sand, lime, water and other ingredients. It is a strong, attractive and damage resistant covering for walls and ceilings. It is an excellent building material for hot areas as it helps to regulate the temperature. It is non-combustible and its surface burning properties include no flame spread and no smoke development.
Currently, there are two distinct types of Stuccoes –
Traditional/Hard Coat Stucco – This is basically cement mixed Stucco. The traditional stucco is durable and able to withstand harsh environments. It is porous and can breathe, so, dries quickly and resists water damage.
Conventionally, lime was used with sand and water. As lime is slightly soluble, the mixture has a self-healing tendency. At present, stuccoes are usually made up of Portland Cement, sand and water resulting in a hard and brittle variety.
To install hard coat stucco, first the substrate is installed followed by a metal lath and then a coat of stucco is applied with a trowel. It is allowed to set and then another coating is applied. Normally, the process involves a scratch coat, a brown coat and a finish coat (may be colored).
Stucco can also be applied on a paper and wire. The coats should be thicker. The first coat (scratch coat) covers the wire. It needs to be scratched as soon as it sets. The second coat (brown coat) gets bonded to this coat and as usual the finish coat is the outermost layer.
Synthetic Stucco – Since 1950s, a number of houses were built using a variety of synthetic materials resembling stucco. Fibers and synthetic acrylics were added to the cement stucco mixture to add strength and flexibility. In general though, the synthetic stuccoes are less heavy and hence, more susceptible to a hard blow. They are a one-coat stucco system unlike the three-coat traditional ones.
The most common one is EIFS or Exterior Insulation & Finish Systems. They are glued or mechanically attached to the substrate and usually composed of three layers. The innermost layer, mostly made up of polystyrene like material, is a foam insulation board. The second layer is a base coating attached to a fiberglass mesh and the final layer is a finish colored coat. It became popular because of its easy installation, low cost and better insulation properties. The only disadvantage is moisture absorption which causes water damage to the building.
A variety of stucco colors/paints are available. Colorants are inorganic pigments which can adapt with the high pH value of cement. They can be either natural like, Ochers and natural earths or artificial, such as man made Iron Oxides. Natural colorants remain unaffected to UV rays and are more pleasant to our eyes. But, the range of shades and the tinting strength is less when compared to manufactured colors. Man made colors, on the other hand, offer a wider range of shades such as dark blues and greens as well as various earthy tones like, yellow, brown and reds. They also possess excellent UV stability due to the presence of inorganic pigments.
How to Repair Stucco Siding on Your Home
Stucco has been use to protect and decorate exterior and interior walls and ceilings for many centuries. Stucco is available in dozens of textures, thousands of colors and is currently the cladding of choice for most new construction and remodel or restoration projects.
The two main categories of exterior stucco that encompass dozens of different systems are Hard Coat Stucco and EIFS (Exterior Insulation and Finish System). Hard Coat Stucco is the preferred system for residential or multifamily construction, and is being used increasingly for commercial projects since it is more economical. EIFS is more commonly used for commercial building projects, but is often also used for high-end custom homes.
Hard Coat Stucco is typically applied in 2-3 coats with a cementitious base coat. Two commonly used hard coat stucco systems are called One Coat Stucco and Three Coat Stucco. Traditional Three Coat Stucco consists of two coats of a cement base and one finish coat. One Coat Stucco is actually a two-coat process but instead of two base coats it consists of one cementitious base coat with one finish coat. In the last few decades One Coat Stucco has become much more popular simply because of the cost. The materials used and application process are virtually the same for both systems, other than the exception of One Coat Stucco taking fewer steps and less time. The design ability and performance between the two systems are also the same, although Three Coat Stucco is typically stronger and will crack less in most circumstances.
The finish coat application of both hard coat systems is the same. There are numerous finish options but they can be consolidated into a few categories which are: Integrally Colored Stucco, Painted Stucco, and Acrylic Finishes. Colored cement finishes or "colored stucco" was the popular choice over Three Coat Stucco for most of the 20th century. It is simply a mixture of cement, lime, sand and pigment. It is inexpensive and easy to apply, however, if the base coat cracks the finish is almost guaranteed to crack. Colored Stucco will stain easily, is hard to repair, and allows water to pass freely through it (which can be good or bad depending on what part of the country the system is applied within). It is usually applied by hand and can achieve virtually any finish imaginable.
Painted Stucco has been around almost as long, and is the majority of the finishes being used today. Painted Stucco is the same mixture of materials less the color, so it is applied the same and will achieve all the textures that integrally colored stucco will. The final step with Painted Stucco is the paint application. The paint, or as some like to call "coating", will look more vibrant and is easier to patch. Color options are vast and it is important that a good quality stucco paint is used. The most desired stucco finish today is Acrylic Stucco or Acrylic Finish. Some will call this system Synthetic Stucco, which is somewhat correct since it is a synthetic finish, however it is not a synthetic system.
Acrylic Finish is available in as many colors as a paint and has the same chemical make up as paint, but is a much thicker application. This does raise the cost of the overall system, but offers many benefits that the other two finishes do not. Acrylic Stucco will bridge most all hairline cracks and does not allow water to travel freely into the system, which is a huge benefit in freeze/thaw zones. Acrylic Stucco will keep it's look and typically will not require any maintenance for many years, whereas painted stucco must be repainted and repaired within a few years. Colored Stucco stains easily, will show every crack and is very difficult to repair.
EIFS is a full synthetic system or what most will call Synthetic Stucco. EIFS systems weigh much less than traditional stucco and are much more flexible. Although most EIFS adhesives and base coats are cement based, they are heavily polymer modified so they are considered synthetic. These type of systems have been used successfully for many decades but are much newer in the stucco world. Most all EIFS systems use EPS (Expanded Polystyrene) insulation board which is usually adhesively attached to the substrate and sometimes mechanically attached. The EPS adds insulation to the wall assembly, absorbs movement better than any other stucco cladding used today, and adds many design options.
The original or traditional EIFS systems all used a cement-based adhesive and/or mechanical fasteners for the EPS, fiberglass netting for reinforcement and to gauge base coat thickness, cement base coat, and an acrylic finish. These systems are known as Barrier EIFS. Since these systems are so watertight, they've had some problems such as not allowing water to escape after it had travelled into the system because of improper application and flashing. The industry quickly designed Drainage EIFS or Water Managed EIFS which some manufacturers had and promoted before these issues arrived. Drainage EIFS systems have been very popular in recent years and include added or altered components such as notched or channeled EPS, plastic trim, trowel or roller-applied waterproof coatings. These systems seem to have remedied the water drainage problem of years past. The finish coat options for EIFS are not as vast as they are for Hard Coat Stucco. Since EIFS is a "soft system" or synthetic system, cement finishes will not work unless they are acrylic or polymer modified.
Most EIFS manufacturers have their recommended systems and will not warranty their products if deviated from the original specifications. Almost every final coat for EIFS consists of an acrylic emulsion and marble or silica sand finish that is hand-troweled over the base coat. Acrylic finish is integrally colored and very flexible. There are a few standard textures that acrylic finishes provide, including Smooth Finish, Sand Finish, and Rilled or Swirl Finish. These finishes, which are expensive, are usually applied in one coat at a thickness of 5/32" or less. Many different textures are possible by multilayering an acrylic finish.