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What Everyone Should Know About Synthetic Stucco

You may have read the recent article in Mobility Magazine about Synthetic Stucco or EIFS (Exterior Insulation and Finish System). Synthetic stucco is a beautiful and popular exterior choice for many, but it must be installed properly to avoid some known issues. As inspectors, we'd like to share the following information, which we think everyone should know about EIFS.

What is EIFS?

Exterior Insulation and Finish System (EIFS), commonly known as synthetic stucco, is an exterior cladding system composed of an adhesively or mechanically fastened foam insulation board, reinforcing mesh, a base coat, and an outer finish coat. EIFS is available in various colors and external textures designed to look like traditional stucco. Its exterior appearance looks almost identical to conventional stucco, although conventional stucco is usually comprised of multiple layers of cement over a wire mesh.

Why is it popular?

Home purchasers are attracted to EIFS because of its majestic look. The exterior cladding makes normal homes stand out and delivers fantastic curb appeal.

Architects and builders are attracted to EIFS because the expanded polystyrene (EPS) insulation used in this product is easily shaped and sculpted. The EPS insulation can be used for making decorative bands, quoins, and other adornments on homes. In addition, EIFS is a competitively priced alternative to conventional stucco or brick siding.

EIFS is also popular because it acts as a great insulator. Besides offering design flexibility, EIFS insulation boards can cover a building’s entire exterior wall space, in essence eliminating any thermal breaks in the insulation barrier. This can reduce energy consumption, reduce air infiltration, and increases interior comfort.


It sounds great! What's the problem? 

Well there is no problem, as long as it's installed correctly. But it turns out that that is more difficult than you might think. EIFS application requires strict observance to the manufacturer’s recommended specifications and guidelines, and involves meticulous workmanship and attention to detail. When improperly applied, the EIFS cladding does not perform its intended function and allows water to infiltrate behind the cladding, where it can become trapped.

EIFS details are procedures outlined by the EIFS manufacturer that provide guidance to the architect, builder, and applicator as to the proper installation of the product. All EIFS manufacturers have details and procedures that builders and applicators are expected to follow. Installation details are typically very similar among EIFS products and EIFS manufacturers, but there are differences.

EIFS must be purchased from an EIFS distributor. The manufacturer or distributor trains applicators and issues certificates stating that the applicator has been properly trained. It is the responsibility of the distributor to ensure that EIFS is sold only to those certified applicators.

An Inspector's Perspective

It is still our recommendation that any home with EIFS be fully inspected by a professional who is qualified to assess the quality of installation and spot-check for top red flags and symptoms of failure. The inspection serves to assess the system and determine if the installation followed the appropriate guide lines. The inspection evaluates how the water is controlled, and how any water that does get behind the EIFS is able to escape and not be trapped against the wood structure. Without proper water controls in place (sealants, flashings, drainage contingences, etc.) water can get trapped and deteriorate the wood framing structural components. The goal of the inspection is to take advantage of the good qualities of EIFS while limiting the pitfalls that can occur if the systems are not installed correctly. If you'd like to know more about how inspectors like those at US Inspect conduct an EIFS inspection, read more here.

​Some Known Issues

Some more specific problems with the improper installation of EIFS are when the foam is placed below grade, or when the system is missing a secondary weather barrier and therefore has an inability to drain properly. To complicate matters, an EIFS applicator is responsible for the application process: attaching the foam insulation to the substrate, applying the fiberglass mesh, embedding the fiberglass mesh with base coat, and applying a finish coat. But a typical EIFS applicator does not install backer rods and sealant, but should install the EIFS so that it is possible to install these critical components. It is the builder who is responsible for subcontracting the backer rod and sealant components.

What's more, flashings around windows, doors, decks, chimneys, and roofs are the responsibility of the builder and his roofer. However, the applicator should recognize improper flashing and not continue the application process until the problem is corrected.

According to the National Association of Home Builders Research Center “This divided responsibility combined with the need for special construction details are alleged as the causes of premature failure” of EIFS. Oh, but that's not all, unfortunately. There are other factors that can also cause failure. You can read more about those specific issues on our site here.


So how exactly does the system fail and allow water infiltration?

The problem with barrier-type EIFS cladding is that the systems rely entirely on their outside surface to prevent water penetration and moisture intrusion. Barrier EIFS does not have an internal drainage provision, and therefore requires excellent design and workmanship to produce a weather-tight and long-lasting system.

​Throughout the United States, a significant percentage of homes clad with barrier-type EIFS began experiencing problems with water penetration and moisture intrusion, primarily around windows, doors, and roof-to-sidewall intersections. The retention of moisture in these systems will invariably lead to damage that frequently goes undetected for an extended period of time.

​In many homes clad with barrier EIFS, water that has entered behind cladding does not evaporate, or “escape,” quickly enough to allow structural members to dry out. The moisture content and temperature inside the wall cavities of these homes often promotes rapid growth of wood destroying fungus, leading to deterioration or rot of the sheathing/substrate. Depending on the size of the home, EIFS repairs can range from tens of thousands to over $100K.

In contrast to residential construction, most high-rise condominiums, office buildings, and stores are made of concrete and steel. While problems with barrier-type EIFS have also been widely reported on these structures, such problems have generally taken a longer period of time to manifest than is the case with wood-framed residential construction.