Exterior Insulation and Finish Systems (EIFS) account for about 10 percent of the exterior walls on new commercial construction. If you’ve ever walked down The Strip in Las Vegas or stayed in a newer hotel, what you think is stucco or concrete may, in fact, be EIFS. EIFS are everywhere. EIFS are also known as synthetic stucco, and Dryvit® (actually the name of a leading EIFS manufacturer).EIFS consist of a layer of foam insulation, which is attached to a supporting wall, and a thin, reinforced synthetic coating system. EIFS look like concrete or stucco, but also can be made to look like stone. EIFS are installed by hand, by plasterers. For large buildings, EIFS can also be made in a factory as panels. Panels are trucked to the site and hung like precast concrete panels.The key to a successful EIFS project lies mostly in three factors. The first is using a qualified EIFS contractor. The second is to make sure all the details of the EIFS, especially at the perimeter, are properly engineered and shown on the architect’s drawings. The third is to have the EIFS manufacturer involved in the installation proc-ess. There are many good brands of EIFS, and the various brands are quite similar in appearance and composition.There are two types of EIFS. The original type is called Conventional EIFS. This type is sometimes also called Barrier EIFS, as it does not have a drainage cavity between the EIFS and the supporting wall. A new type of EIFS is available called EIFS with Drainage. This type does have a drainage cavity between the EIFS and the supporting wall. The drainage cavity is intended to handle incidental leaks by providing a route for the water to get safely to the outside. Almost all EIFS on commercial buildings that are more than 5 to 10 years old are Conventional EIFS.Most problems with EIFS involve water leaks at the perimeter of the EIFS, caused not by the EIFS themselves leaking, but by leaky windows, caulking joints, and flashings.EIFS do not require any special maintenance other than routine inspection for the gradual wearing out of sealant joints, and for damage and cleaning. Being a lightweight material, it’s a good idea to keep EIFS away from high-traffic areas to preclude damage by people, vehicles, and maintenance activities. EIFS can be made stronger by putting extra reinforcing in the coatings, and this is a good idea at balconies, near sidewalks, at entrances, and at parapets. Damage to EIFS can be repaired by removing the affected area and splicing in a new layer of EIFS. Once weathered-in, the patch becomes almost invisible.The main advantages of EIFS are the external location of the insulation, which improves the energy efficiency of the wall over using traditional cavity insulation; the wide ranges of colors, textures, and shapes that can be created; and the high “value” of EIFS (appearance and functionality) for the cost.Although EIFS were developed after World War II in Europe, EIFS came to the United States in the late 1960s, and have since become one of the standard choices for exterior walls for most types of commercial buildings.Robert G. Thomas is an EIFS consultant (www.eifs.com) with offices in Seattle and Jacksonville, FL. He was formerly technical manager at Dryvit Systems Inc., and chairs the U.S. National (ASTM) EIFS Technical Committee.