About Stucco
Although stucco has been around for thousands of years, this article will not address the history of stucco, but rather the different types of stucco used today in the marketplace and how to determine each type of stucco.
In the middle Tennessee area, you we have found 3 different types of stucco applied to homes and commercial buildings; cement based, foam based (EIFS) and cement board based. Prior to 1982, only cement based stucco was used in this area. After 1982 and through 1999, almost every structure built that had stucco applied to it used an EIFS stucco on it. Since 1999, very few homes have an EIFS stucco installed on them due to concerns over moisture issues. Lastly, a very small percentage of homes had a cement board application of stucco used on them which we will detail below.
Over the years, the materials have changed, but the methods of application are pretty much the same.
Cement Based Stucco 
Cement based stucco is a combination of portland based cement and sand that is usually applied onto metal lathe.
The metal lathe increased the strength of the stucco, and if applied correctly, reduced the amount and size of any cracking that occurred. The metal lathe included expansion joints which  allowed for movement of the concrete over time, corner beads which allowed the installer to create strighter corners, and other metal pieces that helped improve the quality of the finished product. Older homes built before 1985 used a metal lathe that rusted because it was not galvanized. The photo to the right shows the use of metal lathe on a current home that Master Stucco just completed.
After the metal lathe is attached, 2 layers of cement is applied. The first is called the scratch coat because the applicator "scratches" the surface so that the next layer of cement will adhere better to the first layer.
The next step is to add the second layer of cement called the "brown" coat. The photo below shows the brown coat being applied on top of the scratch coat.
The cement used today is significantly better than the cement used in the past. It contains microfibers that increase the strength of the cement, and acrylic compounds which allow the cement to expand and contract with less cracking.
One important step after the cement dries is to let it "cure". This takes approximately 28 days. As cement cures, it shrinks and hardens. Hot, dry weather will cause the cement to dry out to fast and create cracking. To help the cement dry properly, it should be kept moist by spraying water on the surface every day.
When the cement layer is dried and cured, the final color coat is applied as shown in the photo to the right.
To determine if this type of stucco has been used on a property, look for metal lathe at places where the stucco terminates, for example at the corners of the walls, around windows, where foundation screens are located, under light fixtures, and at the bottom of the walls where the stucco comes in contact with the soil. If concrete based stucco has been used, you will see the metal lathe at any of these locations. You will also notice that the wall is very hard when you knock on it with your knuckles. The surface will feel as hard as a rock when you knock on it.
EIFS Stucco 
EIFS is an acronym for Exterior Insullation Finish System. This "synthetic" type of stucco uses a styrofoam layer that is coated with a thin amount of cement and an acrylic layer of textured stucco. There were many benefits to using this type of stucco including the insullation benefits, the ease of installing this product, the ability to rasp the foam to straighten out a crooked wall, and the wide variety of design shapes that could easily be created using the foam materials.
The foam layer was either glued onto the wall, or mechanically attached with nails or screws. The photo to the right shows a job where Master Stucco was contracted to install an EIFS stucco exterior on a Huddle House restaurant.
After the foam layer was installed and rasped, a thin cement layer called the "base coat" was applied with a fiberglass mesh embedded into the cement coating. This layer of mesh dramatially increased the strength of the thin cement layer.
The type of cement used on an EIFS wall is different from the type of cement used on a cement based stucco wall. The EIFS cement provided benefits including the ability to apply the texture the next because it did not have to "cure". This benefit also eliminated most of the cracking that were common with cement based stucco applications.
After the base coat layer was applied and dried, the "finish" coat could be troweled on. This layer included a sand texture that could be tinted using paint pigments to almost any color of the rainbow.
The photo to the left shows the final job after the colored finish coating had been installed.
To determine if a building has an EIFS type of stucco applied to it, you can knock on the wall. If the wall sounds hollow, then it is most likely EIFS that was used. You can also check the locations where the stucco terminates, for example at the base of the wall, under an exterior light, or inside the hole where the foundation vents are located. Look for the fiberglass mesh which you will see at one of these locations.
Cement Board Based Stucco (DEFS or DAFS) 
The last category of stucco types that we will address is called "Direct Applied" stucco, which is a hybrid version of cement based stucco and EIFS. The same materials used in an EIFS installation are used in a direct applied stucco wall, with exception of the styrofoam which is replaced with a different substrate.
The substrate, which is the base on which the stucco is applied to, can be other materials that the stucco is compatible with. For example, in the photo to the right, a cement board has been attached to the wall. The same cement used to apply EIFS would be applied on to the cement board, and then the same textured finish would be applied on top of the cement layer.
Other substrates used in stucco include gypsum, dense glass, concrete block, poured concrete walls, brick, and a yellow fiberglass reinforced foam panel. The best way to tell if a particular building has a direct applied stucco system is to remove the cover from an external electrical outlet and look at the materials that the box is surrounded by.
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