EIFS (pronounced eefs) is an acronym for Exterior Insulation Finish Systems. The basic process involves attaching insulation boards to various substrates like sheathing or concrete block, then troweling on a base coat which is reinforced with a mesh fabric. The final process involves troweling on a decorative finish color top coat which is floated to assimilate many varied textures.


  • Expanded Polystyrene (EPS) uses only .002% of the world’s oil supply in its production. Repeat: That is 2/1000th of a barrel of oil!
  • EPS uses 30% less energy to produce than paper does.
  • EPS is 90-98% air.
  • The energy used in the EPS production process is recovered many times over by the energy saved in the buildings in which it is installed. One kg (2.205 lbs.) of EPS saves at least 400 liters (105.6 gallons) of oil over 50 years. In English units that is one pound of EPS saves at least 48 gallons of oil over 50 years.
  • The blowing agent used in creating EPS is not harmful to the environment.
  • There are no CFC’s or HCFC’s in EPS.
  • EPS does not experience any off-gassing which may be harmful to interior air quality.
  • EPS does not contain formaldehyde.
  • EPS does not support common mold or fungi.
  • The energy EPS incineration creates is approx. 16,000 BTU’s/ pound. This is twice the value of coal.
  • Technology now exists to reduce discarded polystyrene by a densification process that effectively reduces its volume by 95%.
  • EPS represents only 0.6% of the volume in our landfills.


  • Research comparing both overall insulating ability and moisture resistance show EIFS with 4-inch foam insulation “outperformed” walls of brick, stucco, concrete block and cementious fiber board in moisture handling with “superior thermal performance.”
  • The proprietary water-resistive membranes used on the new EIFS drainage systems are impervious not only to water, but are superior air barriers as well.
  • According to the National Institute of Standards and Technology, an effective air barrier can reduce buildings annual energy consumption for heating and cooling by up to 40%.
  • EPS that is attached over the fluid applied air and water-resistive barriers in EIFS with drainage systems are attached by adhesive. No fasteners are used that might puncture the membrane. This provides a 100% monolithic barrier that cannot be breached by water or air penetration.
  • EIFS solves thermal bridging created by conventional framing techniques. Insulation is where it belongs, placed to the exterior. This is a little like putting a thermal blanket around the building which provides greater energy efficiency, comfort and cost savings.
  • The R-value of EPS is a constant 3.85/ inch. EPS does not experience thermal drift which minimizes its thermal effectiveness.


  • Using vertical ribbons of adhesive in an EIFS with drainage configuration provides a drainage path for moisture and an airspace that contributes positively to hygrothermal performance.
  • Third party testing shows that a drainage space as thin as a dime drains moisture quickly and effectively.
  • Moisture that may breach the EIFS is insignificant because of the redundant nature of the monolithic liquid applied water-resistive barrier.


  • EIFS does not add or detract from a fire rating. EIFS is perhaps the most tested wall cladding product in terms of its exposure to fire, ignition sources and combustibility.


  • EIFS is addressed by the International Building Codes.


  • EIFS has been used successfully in the Twin Cities for over 30 years. Here are some examples of its longevity:
    • 1978 – Dakota Ridge Best Western, formerly known as Yankee Square Inn, Eagan, MN
    • 1978 – The Arne Chiropractic Clinic, Minnetonka, MN
    • 1980 – Marriott Minnetonka, West
    • 1985 – Macy’s formely Dayton’s, Southdale Mall
    • 1985 – The Marriott Minnetonka
    • 1986 – The Toro Manufacturing Plant, Bloomington, MN
  • Adding reinforcing mesh or high impact reinforcing mesh increases EIFS impact resistance.
  • Finish choices are better than ever:
    • Darker colors are achievable with pigments that remain UV stable.
    • Many finishes now come with Dirt Pick-up Resistance (DPR) technology.
    • Finishes are available that are more moisture resistant.


  • New look finishes now include, luminescent micas, fine aggregates, limestone, metallics, simulated brick and stains that emulate old world finishes.
  • EIFS has always been identified by the architectural community for its ease in creating shapes, bands and other architectural features effortlessly.


Class PB or Polymer Based EIFS

Uses expanded polystyrene insulation board which is adhered to the substrate with proprietary polymer based adhesive that is applied with a notched trowel to the back of the insulation board. In most cases the adhesive that is used in this process is the same material that is used for the base coat and may or may not include portland cement in its composition. After the board has been allowed to set, the surface of the insulation board is often rasped to flatten out high spots and break the surface for a better key of the base coat. The base coat is then troweled onto the surface and a reinforcing mesh is encapsulated by embedding it with a trowel into the base coat. In some instances it is necessary to add more base coat to completely encapsulate the mesh. This process is then followed with an acrylic decorative finish color top coat, floated to the desired texture. Typical thermal values of expanded polystyrene foam board are R3.65/inch. Typically wall thicknesses of these systems are installed from 1″ to 4″. Larger thicknesses are often used to create the look of heavier decorative features, such as quoins, bands, classic entablature and other decorative shapes.

Class PB or Polymer Based EIFS

EIFS with Drainage

In most cases is similar to that of PB EIFS with the exception that a liquid applied water-resistive barrier is installed over the substrate to provide a level of redundancy for moisture protection. These liquid membranes are troweled, roller, or spray applied, generally over a substrate of glass fiber faced gypsum sheathing, oriented strand board or plywood, depending upon the manufacturer’s requirements. Combined with compatible reinforcing fabrics and membranes, penetrations and joints between the sheathing boards are treated to help prevent moisture from breaching the assembly and getting into the cavity or framing of the building. The expanded polystyrene insulation board is adhered with a proprietary adhesive with a notched trowel. The adhesive is oriented in a vertical direction on the back of the insulation board, to provide a medium for the drainage of moisture between the liquid applied membrane and the insulation board. After the board has been allowed to set, the surface of the insulation board is often rasped to flatten out high spots and break the surface for a better key of the base coat. The base coat is then troweled onto the surface and a reinforcing mesh is encapsulated by embedding it with the trowel into the base coat. This process is then followed with an acrylic decorative finish color top coat floated to the desired texture.

There still exist more rudimentary and complex forms of these types of systems, which include mechanically attaching housewraps or building paper, drainage mediums of tangled plastic netting, furring, channeled and compartmented insulation board. While many manufacturers still carry these products, they have fallen out of favor in lieu of the newer more user friendly and advanced technology.

EIFS with Drainage

Class PM or Polymer Modified EIFS

Uses planed or sanded extruded polystyrene insulation which is mechanically attached over a water-resistive barrier and substrate with screws and plastic washers or discs. The reinforcing mesh is generally attached using the same fasteners as are used in attaching the insulation board. The base coat is mixed with the addition of cement, sand, water and a liquid polymer to make a coating that is applied 1/4″ to 3/8″ thick. This is followed by a texture able acrylic decorative finish color top coat. Because of its thickness, coefficient of expansion and contraction and its affinity to similar stucco compositions, PM systems require mechanical control joints to provide stress relief from panel to panel. Typical thermal values are approximately R5/ inch of extruded polystyrene foam board. Limitation to this product’s use is higher cost of materials while being much more labor and skill intensive than the PB system. Competitive in the 1980’s with the more popular PB systems, PM systems are not used to any great extent today, although many manufacturers still carry them as part of their product line.

Class PM or Polymer Modified EIFS


PI in this reference refers to Polyisocyanurate Insulation boards. PI boards generally have a higher density than extruded or expanded polystyrene insulation board, with a higher thermal value of approximately R7/ inch. They are distinct in that the core is yellow in color and a fiberglass facer is installed over the surface of the board. Because of these physical characteristics, PI board is typically installed mechanically with screws and polypropylene discs over substrates generally of sheathing board. Because of the fiberglass facer, rasping of the board is prohibited. Like PB systems however, a proprietary polymer base coat is applied over the surface of the insulation board and a fiberglass reinforcing mesh is embedded into it. Finish is applied in a similar manner to PB EIFS. PI systems have had a larger following in the residential market because of their simplicity of installation. Occasionally they are used in a commercial setting as a substrate for darker pigmented finishes. This is because the in-service temperature of the PI board exceeds that of expanded polystyrene. Like PM systems however, their use have diminished over the years in favor of products that have been developed for EIFS with drainage.


EIFS (pronounced eefs) is an acronym for Exterior Insulation Finish Systems. The basic process involves attaching insulation boards to various substrates like sheathing or concrete block, then troweling on a base coat which is reinforced with a mesh fabric. The final process involves troweling on a decorative finish color top coat which is floated to assimilate many varied textures.

The history of styrene can be dated back to 1831, when it was found that heated storax (the gummy resin in balsam trees) resulted in vapors that contained the basic chemical properties of this thermoplastic resin. Storax has also been found in the mummified remains of the Egyptians.1

In 1839 a German druggist name Eduard Simon is credited with distilling storax resin and obtaining an oil which he named “styrol.” It wasn’t until 1920 that another German, Hermann Staudinger fully understood the ramifications of Simon’s discovery. It was Staudinger who made the first samples of polystyrene which processes developed into the first commercial production by Badische Anilin & Soda-Fabrik aka BASF in 1931.2 Staudinger received the Nobel Prize for Chemistry in 1953 for his research.3

In 1929 the Dow Chemical Company, developed a method of making synthetic polystyrene, although the original concept can arguably be attributed to two Swedish scientists C.G. Munters and J.G. Tandberg who filed for a patent in 1931 and a U.S. patent in 1935. Dow scientists led by Otis Ray McIntire were able to develop a commercial process for the production of cellular polystyrene, now commonly referred to as Styrofoam®. It was patented in 1944.4 McIntire himself has stated that he stumbled upon the process for making Styrofoam by accident while he was trying to find a flexible electrical insulator.3 Ray McIntire was inducted posthumously into the National Inventors Hall of Fame in Akron, Ohio in May 2008 for his contribution joining other such notables as Henry Ford, Thomas Edison and the founder of Dow, Herbert Henry Dow.4

Post World War II Europe provided a prime proving ground for the development of synthetic polymers as a result of petroleum and natural rubber shortages. A German company Sto AG pioneered the first quality synthetic resin wall coatings in 1955 and introduced what is now called EIFS to the European market in 1963.5 EIFS was readily accepted because it provided much needed thermal value to common wall construction of masonry. The necessities apparent in post WWII, new buildings were required to replace the old which spurred a period of renewal. Because most of Europe already had affinity for the trowel applied arts, EIFS fit well into its resurgence. A plus to this scenario was the fact that polymer modification of coatings presents an opportunity for much less cracking than traditional stucco compositions. EIFS is used on 40% of all new European buildings and 80% of retrofitted buildings.6

It is widely accepted that EIFS used in North America was established by a company named Dryvit in 1969. The origins of Dryvit Systems, Inc. can be traced to a handshake agreement between Frank Morsilli, a businessman with a family background in plastering and a German inventor named Edwin Horbach. Morsilli, was duly impressed with the stucco-like product that Horbach twisted in his hands without a single crack and entered a licensing and royalty agreement with the inventor to bring the product to the United States.7 Providence and timing were working in Morsilli’s favor in the early 1970’s when Dryvit was in its infancy. The oil embargo of 1973 created widespread concerns for fuel shortages and energy conservation, which gave a lift to the growing company.

Today, EIFS is perhaps better known because of the aesthetic effects that can be created with the product than by its true virtue of energy performance. Sales for EIFS in 2006 exceeded $313 million and through the 3rd quarter of 2007 were at $224 million.8

  1. Kyung Won Suh and Andrew Paquet, “Rigid Polystyrene Foams and Alternative Blowing Agents,” The Dow Chemical Company, Midland Michigan. Modern Styrenic Polymers: Edited by John Scheirs and D.B. Priddy, 2003,John Wiley and Sons Ltd
  2. John Scheirs, “Historical Overview of Styrenic Polymers,” Modern Styrenic Polymers, John Scheirs and D.B. Priddy, 2003, John Wiley and Sons Ltd.
  3. Mary Bellis, Polystyrene and Styrofoam, About.com: Inventors, http://inventors.about.com/library/inventors/blpolystyrene.htm
  4. Dow Media Sources, Inventor of Styrofoam® Named to the National Inventors Hall of Fame, March 6, 2008, http://www.dow.com/styrofoam/media/current/20080306a.htm
  5. Sto Background Information, http://www.stocorp.com/allweb.nsf/bi
  6. Dynamism and Dryvit, Construction Dimensions, 1982
  7. Dryvit Sold, Construction Dimensions, April 1990
  8. EIFS Industry Members Association, 2007


  • Funded by the US Department of Energy (DOE), through the Office of Energy Efficiency and Renewable Energy’s Building Technologies Program and the EIFS Industry Members Association (EIMA).
  • Field research project conducted by Oakridge National Laboratory (ORNL)
  • Purpose: To validate the moisture and thermal performance of EIFS Wall Systems. And to quantify the performance of EIFS over other types of exterior claddings.
  • Conclusions:
    • Brick and cementitious fiberboard systems tend to accumulate and retain more moisture.
    • Insulation is more beneficial when placed towards the exterior.
    • EIFS with water-resistive barrier coatings performed significantly better than claddings using building paper or spunbonded polyolefin membranes.
    • EIFS with drainage assemblies using vertical ribbons of adhesive, provide a drainage path and air space that contributes positively towards hygrothermal performance of the wall.


  • Liquid Applied WRB’s are applied with no seams: Unlike Housewraps and other sheet goods that are applied shingle style over sheathing substrates, you don’t have to worry about whether the product has been installed properly or with reverse laps that could leak.
  • No fasteners penetrate the WRB: When combined with an adhesively attached Exterior Insulation Finish System, no fasteners such as staples or nails breach the air and water-resistive barrier.
  • Liquid Applied WRB’s don’t trap moisture: Water vapor can condense between a housewrap or building paper and the sheathing of a framed wall. That cannot happen with a Liquid Applied WRB because it becomes integral to the sheathing to which it is applied.
  • Liquid Applied WRB’s don’t tear or break down with UV exposure: Unlike building papers which tear over time from exposure to the elements, liquid applied membranes remain intact.
  • Air Barriers and Energy Savings: The National Institute of Standards indicates that an effective air barrier can save up to 40% in annual heating and cooling costs. Because liquid applied WRB’s are monolithic with no seams or penetrations, they are one of the most effective air barrier choices.
  • Passing moisture: Even if bulk water manages to bypass the primary layer of Exterior Insulation Finish System, the redundant nature of the liquid applied WRB keeps it out of the wall assembly.
  • Penetrations and openings: Windows, AC units and other interruptions in the wall plane are specially flashed and treated by a variety of proprietary methods.
  • Sheathing joints: Sheathing joints are treated by a variety of proprietary methods prior to the installation of the liquid applied WRB.


  • Adhesive Orientation: Adhesive is placed onto insulation boards with notched trowels so that the ribbons of adhesive are in a vertical orientation. When the insulation board is then attached to the surface of thesheathing that has been previously coated with the liquid applied WRB, a drainage plane is created.
  • Independent proprietary research indicates that the drainage space can be as thin as a dime and still drain water quickly and effectively.


  • New look finishes now include: luminescent micas, fine aggregates, limestone, metallics, simulated brick and stains that emulate old world finishes.