How Exterior Insulation and Finish Systems Work

Exterior insulation is often mistaken for stucco or concrete.
Exterior insulation is often mistaken for stucco or concrete.
fredfroese/iStockphoto.com

If you haven't heard of exterior insulation before, chances are you've seen it without knowing it. Exterior insulation and finish systems (EIFS) are common throughout the United States and are easily mistaken for stucco or concrete. You'll find them on all kinds of buildings, from residential to commercial projects: houses, apartments, condominiums, hotels, grocery stores, shopping plazas, office parks, mixed-use facilities, government buildings and more.

EIFS is wall cladding that uses stiff insulation boards on the outside of a wall and a plasterlike exterior covering. Think of it this way: Ordinary insulation is like thermal underwear worn inside, under your clothes to keep you warm and dry, and exterior insulation is like an extra shirt worn on the outside, layered over your other clothes.

There is an array of EIFS types; some rely on an outer barrier to protect against water penetration, while others are designed with a secondary drainage plane behind the insulation. Despite these differences, EIFS varieties are made with the same lightweight, synthetic materials. Panels of polystyrene foam insulation are installed and covered with a base coat. Glass fiber mesh is applied to panels for reinforcement, and a finishing coat is applied last. All together the coatings and mesh are a fraction-of-an-inch thick.

Turn to the next page to learn the upside of using EIFS (and what this special system has to do with post-World War II Germany).

Benefits of EIFS

After World War II, buildings throughout Germany were damaged and in need of resurfacing. Exterior Insulation and Finish Systems (EIFS) originated there and came to the United States in the late 1960s. And for decades, Americans have found a number of reasons to use exterior insulation.

When installed properly, it makes buildings more energy efficient. Initially, it can cost more, but EIFS pays for itself over time. According to Oak Ridge National Laboratory, structures with EIFS can save between 20 percent and 30 percent on energy bills [source: ORNL].

Aesthetics and creative freedom are other perks. Expanded polystyrene (EPS) is part of the system, and it can be cut or molded to create many shapes like arches, columns, window details and sculptures. It can also be used to create elaborate architectural designs, ornate facades or soffits.

This kind of exterior insulation can cost less than using traditional materials. Plus, it doesn't diminish a building's interior square footage since it goes on the outside. This alone can be a significant incentive for projects on high-value land or historical sites -- areas where square footage is at a premium.

Just as EIFS is architecturally versatile, it's also flexible when it comes to installation. Often, foam board is applied with adhesive that won't work in extremely low or high temperatures. By completing the EIFS in panels indoors in a warehouse, the adhesive can dry. Then, the system can be installed in extremely hot or cold places that otherwise couldn't accommodate construction.

There are always two sides to every story. What could possibly deter people from using this product that can be applied in so many different ways?

Disadvantages of EIFS

Exterior Insulation and Finish Systems (EIFS) installation can be technically challenging, sometimes making the cons overshadow the pluses. According to C-Risk, Inc., a risk-management consulting firm, installation problems are due in part to manufacturers' systems all being different: Different systems require different installation techniques. EIFS is either assembled in panels in a warehouse and shipped to the construction site or assembled and installed in the field. Contractors do the installation, so the builder is responsible for finding someone skilled at installation, which can be difficult. Inexperienced workers plus fast-tracked construction can equal compromised EIFS products that leak -- one of the many things that can go wrong during installation.

It's normal for exterior walls to have moisture within them, and most are designed to let water escape or dry. However, once water gets behind the EIFS, it has a difficult time getting out. If EIFS fails its waterproof claim and leaks, it can be extremely difficult to identify who is responsible since there are a number of people who contribute to the integrity of the system: homeowner, manufacturer, supplier, builder, designer, installer, electrician, roofer. In fact, it's common for insurance companies to add full exclusions for EIFS and other ruled-out provisions to their liability insurance policies for this reason.

The EIFS Industry Member's Association (EIMA) says reputable distributors don't sell to the public because EIFS should be installed by a trained professional, not an unskilled homeowner. EIFS is not a do-it-yourself product. Homeowners who have tried to do it on their own have ended up with problems like leaks and holes or worse. This situation has led to a flurry of class-action lawsuits; homeowners who've done their own installation end up suing manufacturers, distributors, builders and any number of people who have participated in the EIFS process. Sometimes building codes disallow the use of EIFS, but residential projects generally have looser standards, making them more vulnerable to EIFS glitches. It may be because of these disadvantages that EIFS is more popular among commercial construction than residential projects, citing one out of every 11 commercial buildings in the United States has EIFS on it [source: DryVit].

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Sources

  • Catlow, Barbara. Director of marketing communications, Dryvit Systems Inc. Interview. March 13, 2009.
  • EIFS Industry Member's Association. http://www.eima.com (March 9, 2009 and March 13, 2009)
  • Grenier, David L. and Jorgenson, William J. "Exterior Insulation Systems: An Overview." Consultants in Risk Management.
  • Hickman, Alan Rudd. "Insurers Slapping EIFS Exclusions on Insurance Policies." Associated Construction Publications. March 5, 2004.
  • Surina, Don. Construction engineer with Sundt Construction. Personal correspondence. March 6, 2009.
  • Widzowski, Linda. Administrator with EIMA. Personal correspondence. March 13, 2009.
  • Zwayer, Gary L. "Building Envelope Design Guide - Exterior Insulation and Finish System (EIFS)" Whole Building Design Guide. http://www.wbdg.org/design/env_wall_eifs.php (March 9, 2009 and March 12, 2009 and March 13, 2009).