Exterior Insulation and Finish Systems
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ABSTRACT
This Monograph is intended to give the leader an understanding of application methods, and the types of reinforcement used in each class or Exterior insulation and Finish Systems (EIFS). It reviews their history ad uses, testing requirements, building code requirements, and other information necessary 10 specify these systems.
INTRODUCTION
This Monograph is presented a general intro¬duction to Exterior Insulation and Finish Systems (EIFS) and their uses in today's construction market. It defines these systems, discusses their origins and current uses, of¬fers a further classification of the types of systems avail¬able, describes application techniques, and provides infor¬mation on testing criteria and building codes.
The objective of this Monograph is to provide the Je8der with a basic understanding of a wide-ranging in¬dustry, and to give a construction specifier the informa¬tion needed to choose and specify the class of EIFS that will enhance a construction project.
EXTERIOR INSULATION AND FINISH SYSTEMS (EIFS)
Definition
The term Exterior Insulation and Finish Systems refers 10 a type of building wall system that provides both insulation, and a weathering exterior surface. These sys¬tems typically consist of a number of components which, when applied as an exterior building envelope provide visua1 aesthetics as well as thermal insulation. )
The system components usually are: an insulation board; an adhesive and/or mechanical fastener for apply¬ing the insulation board to the substrate; a basecoat material; either a reinforcing fabric, which is embedded in the basecoat material, or, an acrylic modified basecoat containing internal reinforcement of random fiberglass ag¬gregate; a synthetic, or a cementitious p1aster-like finish coat which is usually available in a variety of textures and colors; and any applicable accessories recommended by the manufacturer (see Figure I, page 8).
Finish coatings are wet-applied, usually with plasterers' tools or spray equipment. The systems can either be installed directly to the building wall, on the jobsite, or they can be prefabricated, on or off-site, as panels having metal frames. These wall systems may or may not be used with conventional insulation methods, such as batt insulation in the wall cavity or foil-backed polys¬tyrene behind the gypsum drywall.
The most common substrates for EIFS applica¬tion are exterior grade gypsum sbea1hing, concrete block, brick, poured concrete, and metal lath. For other types of substrates, contact the various EIFS manufacturers for their recommendations.
History or the Systems
Exterior Insulation and Finish Systems were developed in Europe over thirty years ago, and they have been used there extensively since World WII. They were introduced in the United States in the late 1960's. These materials are now manufactured and sold by more than 20 companies in this country. They have been used on more than 80,000 new and retrofit projects, and sent over 300,000,000 square feet of wall construction. (2)
Reasons For Using EIFS
Use of an exterior insulation and finish system pennits massive insulation to be placed at its most effec¬tive location-the outermost surface of the building. This lightweight insulation on the exterior saves energy since the building mass remains at a stable temperature, inside the exterior envelope, because thermal bridges are sealed and prevent heat from escaping through the wall system (see Figure 2, page 9). The EIFS also seals potential avenues of water entry. The wall remains dry and insula¬tion values remain constant (3). These systems can also provide savings in the initial design of the building's HVAC system, and in the building's annual energy con¬sumption.
In addition to the energy efficiency that EIFS provide there are also other reasons tha1 these systems are specified: their lightweight nature and ~ of erection; their affordability in relation to other wall systems; their appearance and ability 10 contribute different colors, tex¬tures, and architectural details of the building's design; and because of their proven performance and longevity.
Uses or EIFS
Exterior Insulation and Finish Systems are found on all types of new construction such as single-family and multi-family residential, commercial, medical, institu¬tional, and industrial buildings. Also, hotels, office build¬ings, high-rise buildings, and hospitals frequently use this type of exterior wall system. E1FS can serve as the total exterior wall material, by it can serve as an accent material on fascias, spandrel panels, or soffits.
In retrofit applications energy-intensive build¬ings, tha1 were constructed years ago, can be effectively and efficiently renovated by applying an EIFS as a new exterior skin.
By varying the thickness of the insulation-board component or by the use of Laser cutters, special reveals and shapes can be created for architectural design pur¬poses. Signage, arches, columns, and geometric wall details are frequently used in EIFS applications.
Classifications or EIFS
The Exterior Insulation Manufacturers Associa¬tion (EIMA) has developed a classification system for EIFS. It groups these systems in terms of the protective coatings that they use. There are three classes of systems: Polymer Base (PB), commonly known as synthetic resin¬ based; Polymer Modified (PM), commonly known as cementitious; and Mineral Base (MB).
These three classes of systems are then further distinguished by the type of reinforcement that they use: Externally Reinforced, Cloth. Galvanized Stucco Netting or 3.4-lb Rigid Metal Lath (Type A); Internally Rein¬forced Random Fibers (Type B); and Non-Reinforced (Type C). (4)
The insulation component of these systems is not covered by EIMA's classification system. It is important for the reader to know that the type of insu1a1ion used is unique to each system and is not necessarily interchange¬able between the different systems.
Specifiers should not select an insula1ion type dif¬ferent than the type recommended by the EIFS manufacturer. Vapor transmission values vary between the various types of insulation. This could affect where the dew point occurs within the system which would ul¬timately affect the success of the installation.
Manufacturers' data, in regards to insulation board should be carefully consulted. Most of the EIFS available use expanded or extruded polystyrene, but there are some systems that use isocyanurate or cement-based insulation plasters. (S)
The attachment of the insulation-board com¬ponent can be by adhesive or mechanical methods, or by combination of both. It is recommended that the specific fastening instructions of each manufacturer be consulted and followed.
The use and placement of both vapor retarders and vent tubing in the wall system should be determined, on a job-to-job basis, by qualified mechanical engineers and the manufacturer of the EIFS involved.
APPLICATION METHODS
Applicator Programs
Most of the manufacturers of EIFS have formal applicator training programs, and they require that their systems be installed by contractors who have completed the required training program. Exterior insulation system work is generally under jurisdiction of the plastering trade. By training these plastering mechanics, the manufacturers endeavor to insure that their materials will be applied within the parameters that they have specified. Field Application Techniques
Since EIFS vary in their components and applica¬tion requirements, it is difficult to discuss application pr0¬cedures and be sure that all systems have been covered. It is suggested that the application instructions of each manufacturer be consulted. A general description of the application process follows.
Weather. Instal1a1ion of these systems should be 81 an ambient temperature 81 or above 40 F, and the temperature should be maintained above 40 F for at least 24 hours after application of the wet material. Supplemen¬tary heat is often provided during application in cold weather.
Application or the Insulation Board. The first Step in the application process is the inspection of the sub¬strate to confirm that it is a type approved by the system manufacturer. Also, verify that the substrate is free of planar irregularities greater than 1/4-inch, and that it is sound and free of foreign substances.
Installation of the insulation board is accomplished in various ways, depending on the type of fas¬tening recommended by the manufacturer. In adhesively fastened systems the adhesive is spread on the back of the insulation board, with continuous ribbon around the perimeter, and additional dabs approximately 8 inches on center on the remainder of the board. An alternate method of applying adhesive is to spread the adhesive on the en¬tire surface, of the back of the board, using notched trowel.
When mechanical fasteners are the required type of fastener, method of application and required fastener spacing are specified in the EIFS manufacturer's printed instructions. According to EIMA there should be no less than one fastener per two square feet, and fasteners must be located at framing members. Fasteners may also be pan of ~ reinforcement mesh attachment if reinforcing mesh or netting is used. Some fastening systems require both adhesive and mechanical attachment.
When installing insulation board it is important that all boards be butted together tightly with no more than. 1/16-inch space between board abutments, and that they be applied in running bond pattern with staggered vertical joints. A flush level-surface should be main¬tained. Some types of insulation boards should be rasped to remove any planar irregularities.
Application or the Reinforcement Component. In systems that use a reinforcing fabric, a layer of the basecoat material is spread on the face of the insulation board and reinforcing fabric is completely embedded in this material. The reinforcing fabric should be con¬tinuous at all comers and lapped a minimum of 2 1/2-in¬ches at the fabric joints. The insulation board is wrapped with reinforcement fabric at all termination points, unless trim accessories are recommended by the manufacturer.
Some systems are internally reinforced with ran¬dom glass fit material in their basecoat A four inch or six inch wide glass reinforcement tape is also installed at all board joints, within each panel, and all comers of the panel are also wrapped with the tape.
Some of the polymer base EIFS offer higher im¬pact performance through the use of either high impact resistant fabrics, or multiple layers of reinforcing fabric. Applying the Finish Coat. The basecoat/rein¬forcement fabric layer must be fully cured prior to ap¬plication of the finish coat. The finish is applied by hand trowel or spray to a thickness specified by the individual manufacturer. It is important that a wet edge be main¬tained at all times, and that all mechanics use the same methods of texturing in order to achieve uniformity. Only enough material should be applied so that the mechanic texturing behind the applicator will be texturing wet material (a wet edge). Otherwise a difference in texture (a cold joint) will be apparent Most of the EIFS available have integral color with a variety of color choices. Some of the system's finishes are integrally colored in the manufacturing process. Others are colored through field-mixing with concentrated pigment manufactured from raw materials.
Texture and color can be specified to match an approved sample. Manufacturers usually offer several finish coat aggregate sizes which makes it possible to simulate many appearances.
Problems That Can Occur. Proper installation is essential for the successful performance of EIFS. Poten¬tial problems resulting from poor application are: incon¬sistent color and/or texture if the job is not properly manned and if a wet edge is not maintained; telegraphing of insu1a1ion board joints through the finish occurring if 1he boards are not flush; water penetration into the system through window and roof leaks caused by improperly aea1ed joints; or cracks in the finish because of unlapped reinforcing fabric or improperly embedded reinforcing fabric.
When adhesive is the only method of securing in¬sulation to gypsum shea1hing, the success of the installation is dependent upon the paper not breaking bond with the gypsum. Mechanical attachment is recommended.
Prefabrication
Panelization of EIFS allows year-round applica¬tion, even in colder c1imates. The panels can be fabri¬cated off-site and trucked to the job-site, or, if proper en¬vironmental conditions are met, they can be fabricated onsite. These panels are lighter in weight than most other waJ1 systems, and they can usually be installed with lightweight hoisting systems.
The panels can be erected with any style and gauge of metal studs that are approved for use in curtain wall, infill, or load-bearing use. Exterior grade gypsum sheathing is screwed to the studs, and the EIFS are applied in the same manner as on-site application, except they are applied in a horizontal fashion.
TESTING AND BUILDING CODES
Testing or EIFS
The Exterior Insulation Manufacturers Associa¬tion (EIMA) has listed test criteria for each classification of Exterior Insulation and Finish Systems. The test cri1eria suggest specific tests for evaluation of perfor¬mance levels of 1bese systems. EIMA distinguishes be¬tween tests that test die coatings of these products, and tests that test the whole system.
The suggested tests for the Polymer Modified, Fiber Reinforced (PM-FR.) class with Type A or Type B reinforcing systems include: Accelerated Weathering, Freeze-Thaw Resistance, Full Scale Fire Test. Impact Resistance, Salt Spray Resistance, Sand Abrasion Resis¬tance, and Uniform Transverse Load, to test the complete wall system. Tests for the insulation board are: Density, File Hazard Classifica1ion, Heat Transmission, and Vapor Permeance. (6)
Tests suggested for Polymer Base (PB) and Mineral Base (MB) classes with a Type A reinforcing sys¬tem include: Abrasion Resistance, Absorption-Freeze, Ac¬celerated Weathering, Full Scale Diversified Fire Testing, Full Scale Fire Test. Impact Resistance, Mildew Resis¬tance, Moisture Resistance, Negative Wind Load Testing, Salt Spray Resistance, and Wind Driven Rain. (7)
Building Codes
In most jurisdictions EIFS, in order to be used, must be recognized by the model building code used in that specific region (ICBO, BOCA, SBCCI). Most EIFS are approved by the issuance of an evaluation report is¬sued by a model code agency. Evaluation reports are is¬sued after the wall system, its printed literature, and the results obtained from required testing, performed by inde¬pendent testing agencies, have been carefully evaluated. With the continuing growth of the EIFS industry, it is im¬portant that the expanding list of systems that are accept¬able to the model code agencies be monitored.
CONCLUSION
Although Exterior Insulation and Finish Systems are relatively new to the U.S. construction industry, they are a viable choice as an exterior wall system for all types of buildings. Their performance has been proven on thousands of applications-in all pans of the country. These systems have been tested extensively, and their ap¬plication is performed by trained personnel who are close¬ly monitored by the systems manufacturer.
The EIFS industry is continuing to grow and there are many manufacturers producing a wide-range of systems. It is important that those who specify them are aware of the different types of EIFS available so that they can incorporate this knowledge into their specifications.
Appendix A: REFERENCE FOOT NOTES
(1) Exterior Insulation Manufacturers Association. Classification of Exterior Installation Systems. Washington, DC: EIMA. (pg 1) (2) Creed, Douglas C. 8Mechanical Fastening: A Manufacturer's Response." Construction Dimen¬sions. pg 31 (November 1985).
(3) Stafford, Willis. "Exterior Insulation to the Rescue" Inside Contracting pg 15 (June/July 1984).
(4) Exterior Insulation Manufacturers Association. Classification of Exterior Insulation Systems. Washington, DC: EIMA. (Pgs 3-5) (5) Ibid-, pg 1. (6) Ibid-, pgs 3 &. 4. (7) Ibid-, pgs 3 &. 4.
Appendix B: GLOSSARY
ACCESSORIES- Products such as corner beads and stops that may be used with the various systems avai1able. Should be zinc-coated steel or PVC. See Association of the Wall and Ceiling Industries -Inter¬national (AWCI) standards.
ADHESIVE- Adheres the insulation board to the sub¬strate.
BASECOAT- An acrylic-modified m8ltrial mixed with cement. The ratio of acrylic vs. cement is different depending on the manufacturer of the EIFS. The rein¬forced basecoat serves as a base for the finish coat.
EIFS- Exterior lnsula1ion 8Dd Finish Systems comprised of insulation board, adhesive/mechanica1 fas¬tener, basecoat, reinforcement, and finish coat.
EIMA- Exterior Insulation Manufacturers Association, Washington. DC, an organization comprised of EIFS manufacturers.
FINISH COAT-Functions as the weathering surface and is usually available in various colors and textures. May be Polymer Base (PB); Polymer Modified, Mineral (PM); or Minera1 Base (MB).
INSULATION BOARD- A component of a specific type and density of the EIFS that functions to reduce beat flow through the wall and also serves as the sur¬face that receives the adhesive basecoat
MECHANICAL FASTENERS- Recommended by some system manufacturers, and used to fasten the in¬su1lation board to the substrate.
PLASTERERS' TOOLS- Instruments used by the plastering trade to install and complete EIFS. The tools commonly used are a hawk, a trowel, and variety of floats used for texturing the finish.
REINFORCEMENT- Glass fabric, or random fibers treated for compatibility with other materials in the system, used to strengthen the system.
WET MATERIALS- The adhesive, basecoat, and finish coat components of the system when they are in their initial state, and ready for application.
Appendix C: BIBLIOGRAPHY
Bucholtz, John E., P.E. "Techniques and Comments". Newsletter Washington DC: Exterior Insulation Manufacturers Association. (Quarterly publication, see pub1ishers index for relevant subjects.
Creed, Douglas C. "Mechanical Fastening: A Manufacturers Response. Construction Dimensions, pg 31 (November 1985).
Exterior Insulation Manufacturers Association. Classification of Exterior Insulation Systems. Washington. DC: EIMA. 1983.
Exterior Insulation Manufacturers Association. Guideline Specifications for Exterior Insulation and Finish Systems, Class PB, Type A Washington, DC: EIMA, 1984.
Exterior Insulation Manufacturers Association. Guideline Specifications for Exterior Insulation and Finish Systems, Class PM, Type A and B Washington. DC: EIMA. 1984.
Stafford. Willis. "Exterior Insulation to the Rescue". Inside Contracting pg l5 (June/July 1984).
