Walls & Ceilings Architect/January 2008

In North America, the most common, basic, definition of EIFS is: A multi-layer system consisting of a layer of foam plastic insulation applied over a continuous substrate, and over which is applied reinforced thin synthetic coatings. While there are many variations in EIFS designs, this is the deﬁ nition of basic, standard EIFS. THE DRAINAGE FACTOR In the ‘90s, EIFS, when used on wood-framed buildings, became deﬁ ned as needing to incorporate a water drainage system. This involved some sort of a drainage area behind the foam, and a protective barrier over the substrate. It was dubbed EIFS with Drainage. This is a clever definition, as EIFS with Drainage is nothing more, in essence, than a traditional EIFS with the drainage option added-on. The base EIFS product is the same; it just has additional features. Regardless of whether it is traditional EIFS, or EIFS with Drainage, the fact remains that it is external to the main wall, and thus is an EIFS. Thus the “drainage issue” is not a part of the basic deﬁ nition of EIFS. There are also many hybrid and complex systems, like wall claddings that are somewhat like EIFS. Examples include sophisticated “rain screen” and “pressure-equalized” designs. These are separate special systems like EIFS, yet they are not mainstream EIFS. One of the key components of “real EIFS” is the presence of a discrete, single layer of only insulation. The word “only” means a material that is not anything other than insulation. There are EIFS-like systems that mix stucco with EPS foam beads in a sort-of EIFS “insulation layer.” Is this EIFS? I think it is insulated hybrid stucco. This is not to say that it is a bad product, but it is not EIFS in the North American sense. TYPES OF INSULATION In the North American market we have a narrow view of what is “EIFS insulation.” Almost all EIFS systems in North America use EPS (the socalled PB systems), but many other systems use extruded polystyrene, polyisocyanurate, spray-applied polyurethane or mineral wool. wool. There have even been attempts to make EIFS using ﬁberglass. Outside of North America, the definition of insulation is even more liberal, including insulation made of hay, FoamGlas (a low-density ceramic glass board, used mostly for furnace lining and to scrape clean the grill at hamburger joints), and even cork. The key to the deﬁ nition of EIFS is not the type of insulation used, but that it is a discrete, uniform singleinsulation material. A “true EIFS,” by North American standards, uses thin, reinforced synthetic coatings as the outer layer. The use of totally inorganic (stucco), thick (greater than about 3/8-inch) coatings is not considered to be an EIFS coating, at least in North America. Such systems are sometimes called “insulated stucco,” which is a more accurate description. The use of thick, inorganic coatings changes the performance of the outside surface, and thus affects the way the EIFS is designed and installed. An example would be a 1/2-inch of stucco-like plaster over foam. Such systems behave like stucco. Unlike EIFS, it is brittle and requires control joints. Although an EIFS does not have a substrate as part of the EIFS product itself, a real EIFS always has a substrate as part of the overall wall assembly. It’s a little bit like saying that the concrete foundation is part of the structural steel package for a building frame. There is a connection, so to speak, but they are obviously not the same just because they touch each other. There are types of so-called EIFS that do not have a substrate; a substrate being a continuous ﬂat surface onto which the EIFS is applied. An example of a non-EIFS would be foam sheathing attached directly to studs with no substrate sheathing (such as OSB or a gypsum product). THE ATTACHMENT SYSTEM The attachment system is not part of the deﬁ nition of an EIFS. There are many ways to get the insulation layer firmly connected to the wall structure. In other words, the way in which an EIFS is attached to a wall structure has little to do with whether it is an EIFS. What constitutes a “viable EIFS” in a given market depends not only on what is in the EIFS itself, but also the local cost/dynamics of the construction market. For example, in countries where labor rates are low, EIFS lean toward systems that are more complex, use less expensive materials and are more labor intensive. Such is the case in Asia and other markets. In North America, labor-intensive systems are not cost-effective, and hence the current EIFS–the common PB EIFS–are the mainstay. Some of the more sophisticated EIFS-like systems from abroad offer numerous attributes like higher performance and longevity, but at a higher cost. I think EIFS, with all its performance qualities, is underpriced for what one gets for the dollar, and I’d like to see EIFS used more often, especially on major buildings that need high performance. To recap, in the North American market, EIFS is a discrete layer of insulation with a thin reinforced synthetic coating layer on top of it. This means that “stucco over foam” is not EIFS, nor is stucco with foam beads in it. The insulation material and the attachment methods are immaterial. So, when some insurance or real estate person tells you that stucco with an acrylic EIFS finish as the final coat is EIFS, or stucco-overfoam is EIFS, tell them they do not know what they are talking about, and to read this article. W&C Robert Thomas is a nationally recognized EIFS consultant based in Jacksonville,Fla. He was the manager of technical services for a major EIFS producer, is the author of several books about EIFS and chairs the ASTM committee on EIFS. January 2008 | Walls & Ceilings Architect | 29

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Walls & Ceilings Architecture/January 2008 Contents Trade News Special Spec Sheet Section Making EIFS Look Easy ICFs Convert Greenbuild '08 The Finish Line Cracking the Code

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