EIFS (Exterior Insulation Finishing System) is a non-load-bearing exterior cladding system that has, over the past 70 years, become one of the most popular exterior finish applications for both commercial and residential projects in the U.S.
EIFS was first introduced to the U.S. at the end of World War II and has had many incarnations. Due to technological and engineering advancements, it has become one of the highest-performing systems for building exteriors that exists today.
Understanding EIFS Stucco
EIFS, often referred to as “synthetic stucco,” is installed in multiple layers in simple steps that provide enhanced insulation properties. With versatile finishing options, architects and building designers have the flexibility to create unique aesthetics. EIFS is equally well-suited to traditional exteriors as it is to sophisticated, modern exteriors.
Definition and Components of EIFS Stucco System
The multi-layer construction of an EIFS system is the basis for its superior insulating properties. While manufacturer systems may vary, most are comprised of an expanded polystyrene insulation board (EPS) secured to the exterior wall sheathing with an adhesive. The board is reinforced with an acrylic plaster and fiberglass mesh layer, and finished with an acrylic and polymer coat that is both colorfast and crack-resistant. EIFS is a continuous insulation system with no thermal bridging due to fasteners or other metal components, which helps reduce building costs for heating and cooling.
Layers and Construction of EIFS Stucco
In its earliest form, EIFS was a simple, three-layer system. After many decades in use, the system has been upgraded to improve performance and longevity, and today, most EIFS applications have six layers.The multi-layer system provides more insulation and moisture protection than traditional stucco:
A water-resistive barrier (WRB) over the exterior sheathing to prevent moisture from infiltrating the system.
A drainage plane between the WRB and the next layer (insulation board) to allow water to drain behind the cladding.
Insulation board that is typically (EPS) or extruded polystyrene (XPS), but can also be mineral wool.
A base coat followed by fiberglass reinforcing mesh (fiberglass is embedded in the base coat) for reinforcement and to add crack resistance and protect against the normal shifting of thermal expansion, and freeze/thaw cycles.
A water-resistant base coat and (optional) acrylic primer, which can be tinted.
The final layer is an architectural acrylic finish coat, which can include various textures and colors, to protect the installation and prevent cracks.
Different Types of EIFS Systems Available
There are two basic type of EIFS systems:
Barrier wall system
Wall drainage system
Barrier EIFS Systems
Originally, EIFS was a face-sealed barrier system with no redundant weather barrier on the exterior wall sheathing. The base coat and mesh component of EIFS provided the waterproof barrier at the face of the system. However, without an air / vapor barrier present, improperly sealed penetrations through the base coat could cause leaks.
With today’s more advanced EIFS systems, components of the exterior wall must either be barrier-type systems or be properly sealed and flashed to prevent water from migrating behind the EIFS and into the underlying walls or interiors.
EIFS Wall Drainage Systems
Wall drainage EIFS systems are similar to cavity walls. Wall drainage or water-managed EIFS systems include an air / vapor barrier at the sheathing and a drainage plane to provide a redundant layer of protection and performance.
The weather barrier must be properly flashed and coordinated with all other portions of the exterior wall to prevent water from migrating into the underlying walls or interiors.
Integration of Insulation and Moisture Management in EIFS
In the past, most problems with in-service EIFS installations were related to moisture intrusion. In the mid-1990s, the EIFS Industry Members Association (EIMA) and the International Conference of Building Officials (ICBO) mandated moisture resistance and retention improvements in EIFS.
Current requirements for a WRB (Water-Resistive Barrier) and alternate configurations, including EIFS drainage systems, have addressed these concerns. Between 2005 and 2007, the Oak Ridge National Laboratory conducted studies comparing the energy efficiency, moisture intrusion, and temperature control between EIFS, brick, stucco, and cementitious fiberboard siding. It concluded that drainage EIFS provided far superior moisture and temperature control performance than brick, stucco, and cementitious fiberboard siding.
The proven performance of continuous insulation (CI) systems moved EIFS and other CI systems from a best practice to an energy requirement. The Department of Energy mandates that all states adopt a commercial building energy code that meets or exceeds ASHRAE Standard 90.1-2010. CI systems, including EIFS, are a recognized strategy for enhancing building enclosure thermal performance and durability.
Advantages of EIFS Stucco
Energy Efficiency and Insulation Properties
EIFS creates an attractive finish that is adaptable to virtually any architectural style, however, it is first and foremost a CI. The properties of CI mean that EIFS has the unique ability to provide a level of thermal efficiency that no other cladding system can duplicate. Fewer transitions and penetrations throughout the system prevent heat loss through walls. From performance to overall environmental impact, EIFS provides exterior finish qualities that other materials simply can’t match.
EIFS construction delivers a cost-effective, highly insulating building envelope that reduces energy consumption, to provide R-values up to ~25. When compared to the maximum R-value for brick at ~12, EIFS offers two to three times the typical insulation values found in brick-clad structures. In commercial construction, a reduction in base heating or cooling demand may make it possible to downsize HVAC systems, in order to reduce initial costs and improve energy efficiency.
Design Flexibility and Aesthetic Appeal
EIFS is one of the most flexible mediums available for exterior finishes and it is compatible with a variety of materials which can create enhanced opportunities for aesthetic appeal:
Integral colored synthetic finish is standard, for limitless color options.
Smooth / sanded textures are standard and issue-free.
Multi-layer application process and acrylic materials minimize surface cracks.
Architectural foam shapes can be integrated to provide more design options.
Durability and Resistance to Weather Elements
Unlike many other exterior finishes, EIFS rarely needs painting. The exterior color of the finish coat is integrated into the applied system, so the color is consistent throughout.
The acrylic components of the EIFS exterior coat give EIFS superior resistance to fading, chalking and yellowing. An EIFS exterior can be painted, so the original color will resist fading and will maintain its original appearance over time. The same acrylic components that preserve the finish color also have excellent resistance to dirt, mildew and mold, for a building exterior that maintains its original appeal. When required, the EIFS exterior can be cleaned with manufacturer-recommended cleaning products, or by hose.
The crack-resistant nature of the acrylic finish helps to resist the effects of wind-blown debris, with EIFS passing stringent Miami-Dade County missile testing, that reflects virtually no impact in hurricane-type weather. If the walls expand or contract with temperature changes or during freeze-thaw cycles, the resilience of EIFS protects the surface from most surface cracking issues commonly associated with traditional stucco, concrete, cementitious cladding, or brick exteriors.
Improved Indoor Comfort and Noise Reduction
Control of the building envelope’s thermal energy flow and moisture is critical for energy conservation, along with occupant comfort. Modern EIFS configurations offer both energy efficiency and air and moisture control. The continuous insulation component of an EIFS installation provides superior protection from outdoor temperatures when compared to most other cladding systems, by keeping cool spaces cool in warm weather and protecting occupants from the cold during the winter season.
Not a great deal of information is available about EIFS and sound transmission, however EIFS installations can offer some noise reduction. To a limited extent, separate layers of sound blocking materials, such as sheathing, and the EIFS surface material, with a cavity that contains sound absorbing material, can improve sound blockage.
Cost-Effectiveness and Installation Efficiency
It is important to consider the cost of materials and installation when comparing exterior cladding. EIFS can be more time-consuming to install than traditional stucco. However, EIFS has lower lifetime costs, including maintenance and repair, and also lasts longer. This makes it more cost-effective over the long term.
Applications of EIFS Stucco
Residential Buildings and Homes
The newest generation of EIFS provides one of the most energy-efficient exterior claddings available. Interior temperature of homes can be maintained more easily due to the continuous insulation properties of EIFS.
Commercial and Office Complexes
The chameleon-like aesthetics of EIFS make it a popular choice for commercial projects. It is easy to achieve a sophisticated and sleek façade to blend with virtually any design style.
Institutional and Educational Facilities
EIFS provides a safe, sturdy, durable exterior for institutional and educational facilities. Reduced maintenance costs, enhanced energy efficiency and the ability to outlast many other types of cladding make EIFS an excellent option for these projects.
Hospitality and Retail Spaces
An endless option of colors and textures for EIFS exteriors provides the versatility required to reflect the brand and personality of hotels and restaurants, as well as the unique characteristics of modern retailers.
Retrofitting Existing Structures
EIFS is one of the most adaptive systems available for retrofitting and revitalizing existing structures. Buildings can benefit from a renewed appearance, while also delivering enhanced energy efficiency to older buildings.
Considerations for EIFS Stucco Selection
Climate and Weather Conditions
Different types of EIFS may perform differently under the same climate and wall design conditions. AWCI provides detailed information about EIFS and water vapor. For more detailed information about EIFS performance across climate zones, please view this article from Construction Specifier.
Building Codes and Regulations
Minimum requirements for specifying and installing EIFS are provided in ANSI/EIMA 99A-2017. The standard includes generic materials, details, and design considerations for EIFS and EIFS with drainage.
Moisture Management and Drainage Requirements
EIFS with drainage is a building-code-compliant cladding system that incorporates an air/water-resistive barrier and flashing details to evacuate incidental moisture that may enter the wall cavity.
EIFS manufacturers should be consulted about the performance values of the systems they offer. According to EIMA, manufacturers are required to provide the following support for their systems:
Specialized technical support with a deep knowledge of system design
Architectural details specific to the wall system
System testing for performance validation
Third-party building code compliance recognition of system warranties
Maintenance and Cleaning Considerations
Individual manufacturers provide maintenance and cleaning guides with recommendations for their EIFS products. However, all systems should be inspected periodically to ensure that all system components are intact and functioning correctly.
Compatibility with Other Building Systems
Aesthetically, EIFS is beautifully compatible with other exterior claddings, and provides an excellent option for additions or retrofitting. System components, however, from different manufacturers, are not designed to be used interchangeably. For proper function, EIFS should be architecturally designed and installed as a system. The materials and installation methods can vary considerably based on EIFS manufacturers. Manufacturer recommendations should be followed.
Installation and Maintenance of EIFS Stucco
For specifications, installation instructions, and details specific to a particular EIFS system, and maintenance, individual system manufacturer recommendations should be consulted.
Pre-Installation Preparation and Considerations
For design considerations regarding limitations of use in high wind-load areas, fire rating and fastener use, please visit the EIMA site. General design considerations are available at ArchDaily.
Proper Installation Techniques and Best Practices
The benefits of EIFS exteriors depend on the proper installation of the system, making sure that everything is correctly installed for necessary drainage. A guide for EIFS wall construction may be downloaded at BuildingScience. Click here for an excellent best practices guide for Canadian EIFS installations.
Maintenance Guidelines for EIFS Stucco
According to EIMA, EIFS should be inspected periodically to ensure that system components are intact. Flashing and sealing should be checked to make certain that the building envelope remains watertight. Repairs to damaged or missing flashing should be made immediately to protect the installation.
The exterior finish may be cleaned with mild soap and water, but should not be cleaned with solvents, wire brushes, or by pressure washing. Manufacturer guidelines should be followed for the recommended cleaning procedures and maintenance.
Click here for additional maintenance and cleaning guidelines.
Repair and Remediation Options for Damaged Areas
Maintenance of EIFS exteriors and sealants at penetrations or terminations is critical to the performance of the water-resistive characteristics of the system. Manufacturers publish recommended repair methods specific to their systems. Repair for holes and cracks are simple and should be addressed as soon as discovered to ensure the continued performance of the installation. Maintenance of joints sealants is the same as for other types of exterior claddings, except that care must be taken to prevent damaging the EIFS finish when existing sealants are removed.
Case Studies: Real-Life Examples
EIFS cladding offers design flexibility and opportunities for custom applications that showcase the skill and vision of architects and designers. Superior energy efficiency and low maintenance requirements make these systems well-suited to both commercial and residential applications.
Lido Beach Towers, Long Island, New York
The 1929-vintage hotel, which was converted to condo ownership in 1981, suffered from numerous thermal and water leaks in its stucco-on-terracotta block walls. Repeated temporary repairs were short-term at best. With the assistance of Sto, the homeowners found a permanent solution with EIFS as a retrofit strategy for the aging and deteriorating building. StoThermTM Premier NExT® EIFS was installed as a “second-skin” approach, which is an ideal plan for inhabited, operational buildings. In an unexpected twist, the system not only provided a solution for the leaks and moisture issues, but also delivered energy savings of approximately 33%.
Mary Our Queen Catholic Church, Peachtree City, GA
The church posed a challenge to Atlanta-based Harrison Design. The building owners - the Archdiocese of Atlanta - hoped to create the elegant look and feel reminiscent of older, iconic, world-renowned structures. A Finestone/Sika EIFS system was chosen for its ability to provide a limestone appearance. The high-performance system features continuous insulation with a continuous air and water-resistive barrier. The highly durable and weather-resistant finish allowed the contractor to achieve the desired exterior appearance and reduce energy and maintenance costs.
Discussing the Benefits and Challenges Faced In Each Case
The ultimate challenge for the Lido Beach Towers project was to complete repairs to provide a durable, attractive and high-performance exterior, while occupied. The project was comprised of 184 homes. All homeowners were able to remain on site while the construction took place. An EIFS retrofit solution is one of the few types of exterior retrofits that can be completed in harmony with a fully-occupied and functioning building without interruption.
The flexible design options and ease for incorporating architectural features allowed Harrison Design to create an old-world interpretation of a stunning church combined with the “new-world” performance features of EIFS. The Archdiocese did not have to sacrifice the beauty of the façade to gain the reduced energy and maintenance costs inherent in EIFS.
Discover the Best in EIFS Stucco for Beauty and Function with Acelab
EFIS provides architects and building designers with durable, long-lasting finish options for both commercial and residential projects. EIFS systems offer versatile aesthetics and can easily provide sleek, monolithic exteriors or detailed, traditional features to blend with virtually any architectural style. The continuous insulation components of EIFS makes it one of the most energy-efficient cladding systems available today.
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