Figure 1 is an example of an EIFS impact failure (Photo Credit: InspectAPedia.com)
EIFS stands for "Exterior Insulation and Finish System." Popularity of this system came about because of its ease of installation and the benefits EIFS provide, but with time failures began to arise. A typical EIFS failure can be seen see in Figure 1. Historical cases have linked most problems to environmental conditions that eventually lead to moisture intrusion through the various components of the EIFS system. However, manufacturers of these systems proclaim that if their products were installed according to their instructions these failures would not occur.
The damage from these failures can be minor or catastrophic, costing an unprecedented amount of money to fix each year. Research has led to refinements in the types and techniques used for installation and maintenance of an EIFS, which can greatly improve the performance characteristics; limiting failures and reoccurring problems. The most predominantly used EIFS system currently in the industry is EIFS with Drainage.
Exterior Insulation Finish Systems (EIFS)
EIFS are synthetic stucco exterior cladding systems that are composed of one layer of exterior insulation board with two coats of finish. EIFS are designed as a barrier type wall system, which means that the insulation within the system is attached directly to the structure of the wall. Unlike traditional cladding like concrete, brick, and glass, EIFS components are proprietary and have a relatively short history within their respective industry. For these reasons, the installation procedures, sequencing and methods may also vary between manufacturers. If materials are not compatible and apt for installation, poor performance may result.
This exterior building system, if installed properly and if no damage occurs to it, creates a water-tight skin that is essentially leak proof for the life of the structure. Otherwise, when leaks occur, water becomes trapped within leading to severe insect damage, rot, and mold problems. Assuming that the building envelope will remain undamaged, whether it be from impacts or improper installation, over its lifetime is a fallacy and should never be expected (Friedman, 2012).
Components of the system are explained in detail below and these components can be seen in Figure 2:
Substrate. This layer is placed over stud walls, concrete walls, or masonry walls. Oriented strand board, plywood, gypsum board, cement board, DensGlass Gold, and polyiso board have all been used.
Adhesive or Mechanical Fasteners. Mechanical fasteners pass through the insulation board to the substrate. Adhesive fasteners are applied between the insulation board and substrate. The two types of fasteners are typically used together.
Fiber Reinforcing Mesh. Fabric or fiber reinforced mesh is commonly found within the base coat.
Base Coat. A layer that consists of fiber-reinforced or fabric-reinforced mesh and a cementitious compound. Base coat properties and quality finishes influence the durability of an EIFS more than any other component, making it the most important of all components.
Finish Coat. Commonly an acrylic "stucco type" or aggregate based system.
Figure 2 is a section view of a barrier type EIFS system(Photo Credit: dspinspections.com)
Origin of EIFS
This system was first developed in Europe after the Second World War to accommodate immediate reconstruction of war tattered cities. When energy sources became limited, retrofitted wall systems that could improve insulation properties of existing walls led to the development of EIFS. Early studies indicated that using 2 - 4 inches of external insulation was estimated to provide 30 percent more energy efficiency than a similar amount of insulation placed within a wall. In addition to energy bills being lowered, placing insulation on the exterior of a building reduced temperature differences between the habitable interior and the exterior. This lowered temperature differential reduced the tendency for components to move, crack, and offered lanes for moisture to penetrate through the building envelope. Because of its ease of installation and flexibility it became a popular product for exterior retrofits.
The system eventually spread across the Atlantic and the first use of EIFS in the United States was in 1969 by Dryvit System (Hall, 1). Dryvit and their competitors focused efforts on the commercial building market sector through the 70's and into the 80's. Then, companies began to implement this system in the residential market. By 1994, 35% of new homes were being clad with EIFS (Hall, 3). The first identifiable problem in the thriving market was due to quality control problems.
One testing and evaluation study was performed by an American Institute of Architects (AIA) Task Force in Wilmington, North Carolina in 1995. 2,009 homes were inspected which involved 19 different builders and 12 different EIFS manufactured systems. Of those inspected 68% had improper or no sealant joints and 94% suffered from some degree of water intrusion. The cause of the problem was determined to be an inadequate design and poor water management details that had no drainage plane for water that enters the system. A lawsuit was filed against the manufacturers and some of the major installers; most leading to settlements (Hall, 3).
With over a billion square feet installed and a high degree of acceptance it is likely that the relatively new system has been under close scrutiny (Lampo and Williams, 11, 1995). With less than 50 years of existence in the United States there has still been sufficient evidence that the characteristics of EIFS -- flexibility, versatility, light-weight, and low-cost -- will continue to be valuable assets as we proceed though the 21st century.
Properties of EIFS
The ability to install EIFS cladding onto large areas without too many joints or thermal bridging instances is one of many design appeals. Other advantages include:
Light weight
Aesthetic appeal (including multiple colors and textures)
Substantial insulation properties
Retro-fitting capabilities
Low cost
Exterior installation
Minimal thermal bridging
Versatile Design
Figure 3 to the right shows EIFS in its various stages of application.
Figure 3. Stages of EIFS Application, Bethany Beach, DE(Photo Credit: Prof. Kevin Parfitt)
EIFS System Types
The first type of EIFS developed (known as Barrier EIFS) consisted of an insulation board fastened to a substrate, glass fiber reinforcing mesh, a base coat that also acted as a weather barrier on the face of the insulation, and a textured protective finish. In response to the large number of water penetration failures occurring behind the weather barrier a second generation of EIFS was developed -- EIFS with Drainage.
The following EIFS systems are the six basic types as found in Hall, 1-2:
Class PB (Polymer Based EIFS) - utilizes expanded polystyrene rigid insulation, a reinforcing mesh embedded into the base coat, and typically a 1/8-inch thick coating of synthetic stucco.
Class PM (Polymer Modified EIFS) - has expanded polystyrene rigid insulation, a reinforcing mesh placed over the surface of the insulation, and a 1/4-inch to 3/8-inch thick base coat. This system was originally produced to resist impacts.
DEFS (Direct-applied EFS) - this is an exterior cladding that has no insulation that can be installed directly onto substrates. It is typically used on soffits, stairwells, balcony walls, and other places that are regularly exposed to impacts.
OCS (One Coat Stucco) - is placed similar to traditional stucco, using metal lath or stucco netting, but utilizes a modified stucco mix that is polymer based and can be applied right from the bag.
Quick R - is a polyisocyanurate rigid wall insulation that is placed under barrier EIFS. It is typically used in retrofit applications to allow for masonry block to meet new energy codes.
Drainage EIFS - is the newest system, introduced to the market in 1996. In these polymer based systems the insulation boards are grooved to allow for water to run down the wall to weeps. A drainage plane is installed between the insulation board and substrate.
Common Problems
There are typically a staggering number of problems in a building, but the ones that cause most concerns usually result in aesthetic or structural damage. For exterior insulation finish systems most performance issues are found when a thorough investigation of the skin of the building is carried out. It is easy to point out problems by simply making notes of any obvious water infiltration points or possible future infiltration locations - usually cracks or deteriorated joints.
Unlike most other rain screen cladding systems, most barrier EIFS system types do not provide a capillary break or a drained cavity. Therefore, imperfections and even planned penetration locations in the surface, leaves EIFS susceptible to multiple moisture problems. In the following sections, commonly found problems will be pointed out and explained.
Cracking
Cracking in EIFS systems allows for for water to penetrate the system. Cracking is common of EIFS at corners, windows, and door openings; especially when moisture is present in the system. Figure 4 is an example of cracking in the top layer of EIFS. Thin base and finish coats are often found to be reasons in which cracking occurs in these systems.
Figure 4 is an example of a surface crack in an EIFS(Photo Credit: InspectAPedia.com)
Surface Wetting
Some failures, like delamination of the finish coat, can be caused by the wetting of the finish coat. There have been cases where the finish coat had been pulled off by accumulated ice adhered to the surface. There are also documented cases where the insulation behind the finish coat, and the backer rod behind the sealant, were saturated. Where snow was found in prolonged contact with EIFS surfaces, delamination of the finish coat was commonly observed (Nelson & Kroll, 15, 1996).
Moisture Penetration (aka Water Intrusion)
Most intrusion has been found to occur around window openings and similar interfaces. Most often, moisture enters the system from flashing's, or lack thereof, above the fenestration's, through cracks, through failed joints, from moisture present on the interior of the building, and through the face of the EIFS. Figure 5 shows a poorly constructed/fix to a corner detail of an EIFS, which eventually led to water penetration.
The four most predominant moisture transport mechanisms are (Hall, 6):
Liquid Flow. This type of movement is the direct influence of a driving force such as gravity, surface tension, or air pressure differentials. These forces push water through openings in the envelope.
Capillary Action. This occurs as a result of moisture movement through porous materials.
Air Movement. An air pressure differential paired with drives moisture through the assembly.
Vapor Diffusion. This is the movement of moisture in its vapor state through a material.
In one instance, water entered an unfinished joint, traveled through the insulation, and leaked into the interior causing extensive drywall and carpet damage (Nelson & Kroll, 15, 1996).
Figure 5 is an example of a poor water management due to improper construction techniques(Photo Credit: InspectAPedia.com)
Condensation
The accumulation of water through condensation has been found to cause damage to the supporting sheathing. If the dew point resides within the supporting wall the insulation within that wall can very easily be damaged by moisture. Even when the EIFS and support system can withstand the condensation that occurs, the EIFS becomes more susceptible to stresses caused by freezing and thawing.
The space behind the EIFS may be a place where water becomes trapped because after water enters the space it is unable to escape. The vapor impermeable materials that reside on both sides of the space eliminate the chance of evaporation and drying.
Mold
The Wisconsin Department of Health has issued a health advisory connecting EIFS as a source of indoor mold infestation and mold-induced illness (Hall 7).
Impact
EIFS is usually a relatively thin, brittle, coating applied over a soft substrate they are highly susceptible to damage by impact. The result of damage is unpleasing aesthetics, but they are also undesirable because cracks and holes allow for water to enter and damage the system.
The material may look like concrete, stone, stucco, and other similar materials, but EIFS have a relatively low tolerance for impact. It is common to see additional reinforcing mesh on places that are subject to damage. Areas near grade have been found most often documented as the places where damage occurs. Other documented impact damage includes damage from window washing stages, falling objects, shopping carts, etc. Figure 6 shows an example of impact damage to EIFS.
Figure 6 illustrates damage caused by a weed-whacker(Photo Credit: InspectAPedia.com)
Substrate Problems
This is thought to be the most costly and serious type of EIFS defect. Substrate is regularly exposed to water damage because of cracks and sealant failures, which are a common and reoccurring problems with EIFS. Oriented strand board (OSB) is most commonly used as a substrate for EIFS systems, but other substrates include plywood, gypsum board, cement board, DensGlass Gold, and polyiso board. When gypsum wall board is used, water within the system will cause the paper to debond from the gypsum; leaving the gypsum to swell and weaken. The EIFS insulation layer then has nothing solid to bond to.
More often than not, this particular problem does not originate from the EIFS, but from faulty windows, open sealant joints, lack of knock-out flashing, and loose and improperly installed flashing. Figure 7 is an example of improperly installed flashing at a roof/wall junction that led to the presence of water and serious leaking within the walls of the home.
Figure 7 shows improperly installed stepped flashing that led to substrate problems in an EIFS building(Photo Credit: InpectAPedia.com)
Attachment Deficiencies
Substrates are not typically marketed or supplied by EIFS manufacturers and selection guidelines are of very limited. Design professionals are responsible for the selection and installation requirements of the substrate, including the way in which it is attached. Specification requirements for fastener type and spacings to attach the substrate must be based on structural design loads. Failure to attach the substrate adequately can lead to the substrate being blown off the side of buildings.
Sealant Failures
Joint sealant is not commonly supplied by EIFS manufacturers, but its installation and performance are vital to the success of the system. As mentioned above, most water intrusion failures are caused by either the absence of sealants or improper application of sealants. Sealant failures include tears, uncured sealant, and other defects not unique to EIFS joints and can be found in many cladding systems.
The four types of sealant failures that follow are those that are most commonly found:
Adhesive failure. When the sealant loses its ability to stick to the sides of the joint. Causes include incorrect sealant choice, too little sealant used, excessive joint movement, and poor preparation.
Cohesive failure. When the sealant fails. Typically caused by aging of the sealant,improperly sized joints, or low quality sealants.
Substrate failure. When the surfaces that the sealant is applied between fails.
Three-sided adhesion. This is a failure because the sealant cannot properly expand and contract when adhered to three surfaces, typically caused by the lack of backer rod.
Poor Workmanship
Figure 8 is a crack in a V-groove(Photo Credit: qualityoneinspection.com)
A study by the Department of Housing and Urban Development (HUD) found that many common deficiencies are caused by poor workmanship, such as (Hall, 2-3) :
Thin base coat. Due to applications of base coats thinner than the manufacturer's recommendations.
Exposed mesh. Which results in exposure to moisture and lowers the systems impact resistance. This often happens in conjunction with thin base coat.
Sealant failures. Most are cohesive failures. These are caused when the finish coat softens due to moisture intrusion are no longer able to provide a good seal.
V-groove cracks. V-grooves add decorative effects. These problems are most common when these joints coincide on the insulation board joints beneath. Figure 8 is an example of this types of failure.
Cracks at openings. Typically caused by stresses at inside corners.
Board joint cracks. Occur over the gaps between boards and worsen as reinforcing mesh loses tensile strength.
Case Studies
A 34,600 square foot three building complex located in northern California (Maino & Keclik, 1)
All three building were single-story wood framed structures on shallow concrete foundations with slab-on-grade floors. The building envelope consisted of wood stud walls covered with 3/8-inch plywood sheathing, glass fiber faced gypsum wall board, and EIFS. The EIFS was made up of a 4-inch expanded polystyrene (EPS) insulation adhered to the gypsum wall board, which was anchored to the underlying wood framing. The EPS was covered with a thin polymer based (PB) coating, the thickness of the PB was dependent on the risk of impact. The joints between the EIFS and the fenestration units were sealed to the EIFS finish coat with a urethane-based sealant. To accomplish an accurate assessment of the building, the company conducted interior and exterior surveys as well as water testing and destructive openings at representative locations.
The main observations of the survey revealed, but were not limited to:
Several locations with improper sealant joints and occasional failure of sealant joints between windows and the EIFS.
Cracking in the EIFS at corners of wall openings.
Vertical cracking at the base of the EIFS.
Drainage directed toward the building, creating an excess of ponding.
It was concluded that the EIFS system could have performed properly if attention to manufacturer and industry standards had been followed. The major cause of water intrusion on the building was the lack of attention to important details, such as window-to-EIFS interfaces.
Exterior Insulation and Finish Systems on U.S. Army Facilities (Lampo & Trovillion, 7).
Army facilities have increased the use of EIFS because of the cost effectiveness, insulation efficiency, and low-maintenance finish. Several failure types have been identified, such as delamination and extensive cracking typically caused by design and/or installation deficiencies. The report provides an analysis of four main problem areas: 1. mechanical damage, 2. system cracking, 3. design issues, and 4. construction deficiencies. It was found that most problems were minor, and that most, if not all, could have been prevented or corrected by relatively simple maintenance and repair procedures. Recommendations are made at the end of the report to help prevent the four main problem areas explored.
EIFS Training and Inspection Programs
There are a number of different training and inspection programs that have been developed to help educate those working with EIFS. A few example follow:
EIFS Doing It Right. This program is a national, standardized education and certificate course available from the Association of the Wall and Ceiling Industry (AWCI). It is a two-day course that focuses on generic EIFS installation according to industry standards. Instruction includes essential knowledge and techniques for proper EIFS installation and inspection.
Course Topics Include:
Industry Standards and Specifications
Material Storage and Temporary Protection
Substrates and Efflorescence
EIFS with Drainage and Flashing
EPS Boards, Mesh, Basecoat, and Finish Coat
Adhesive and Mechanical Attachment
Joints, Sealants, and Repairs
Inspection: Philosophy, Scheduling and Methodology, and Reports
The purpose of a visual inspection is to is to detect any potential problem area, which may permit water leakage and consequential damage. The inspector should develop a comprehensive checklist to check for:
Visual signs of water penetration on the interior of the building.
Damaged areas of the EIFS.
Deficiencies in the joint sealant.
Damaged or loose flashing.
Improperly installed building components that penetrate the walls.
Adjacent building components.
Poor implementation of standard water management techniques and details.
The Future of EIFS
Since its introduction into the indursty more than 40 years ago, many improvements have been made to EIFS, including:
Validation through Studies and Tests. After conducting experiments, researchers from the Oak Ridge National Laboratory have concluded that EIFS is the best performer in relation to moisture control and thermal efficiency when compared to brick, stucco, and cementitious fiberboard siding. Fire tests have also been conducted to meet current building code requirements. EIFS has passed fire resistance, ignitability, multi-story corner tests; meeting standards set forth for each test.
EIFS with Drainage. This relatively new EIFS system offers the same benefits of older versions of EIFS, but contains a drainage cavity and provides protection to the substrate with the use of a liquid-applied water resistive barrier (WRB).
Improved Sealants. Sealants that are used to fill the joints in EIFS are continually improving. It is recommended to use low modulus sealants that maintain their properties when exposed to ultra-violet light. Also, sealants should comply with prescribed ASTM Test Method G1382-97; most sealants meet or exceed this standard.
Improvements to Finishes. Continual improvements are being made in EIFS finishes. One example is – a finish that allows moisture that accumulates between the finish and base coat to drain harmlessly to the exterior. Another example is a glossy finish that allows built-up dirt to be washed away with rain. In addition to the performance improvements mentioned earlier, manufacturers can now match any color and provide multiple finishes including the appearance of brick and metal.
EIFS Listed in Building Codes. Since 2009, the International Building Code and International Residential Code provide information on the use of EIFS.
Insurance for EIFS. Affordable insurance now exists for EIFS. As more insurance agencies become aware of the benefits of EIFS more insurance options will become available.
Streamlined Evaluation Reports.
EIFS Claims History
The litigation and claims history of EIFS has decreased considerably over recent years. A study by EIFS Industry Members Association (EIMA) has shown a steady decline in the number of claims brought against four major EIFS manufacturers.
Prevention/Solutions
There are a considerable amount of failure modes that exist for an EIFS. With the help of research and failure assessments solutions have been developed to improve the durability and longevity of the systems. Most solutions are preventative means and methods recommendations that should be introduced during design and construction.
Condensation
If the material that supports the insulation can be damaged by moisture, the EIFS insulation thickness should be substantial enough to eliminate the possibility of the interior air reaching the dew point. The most extreme winter conditions should be used in the formulation of the insulation thickness.
Impact Resistance
To improve impact resistance performance companies have developed a high impact mesh. This heavy mesh does provide additional resistance, but has proven to be inadequate for areas that are prone to severe and continuous impacts.
Substrate Problems
Gypsum sheathing is extremely vulnerable to water damage when cracks and sealant failures are present. Even if extreme caution is taken to protect the gypsum board from exterior water penetration, condensation, and interior flooding the chances of providing a perfect seal are very slim. Because cracks and moisture intrusion is inevitable with an EIFS it is recommended to avoid the use of gypsum as a substrate.
Sealant Failures
Before a sealant is specified the sealant and EIFS manufacturers should be consulted and compatibility should be assured in order to ensure a successful system.
Proper joint geometry, which includes bond breaker materials, is a necessary material for failure prevention. The use of open-cell backer rod is not recommended because of its tendency to transfer and hold moisture. Bonding surfaces shall be prepared with manufacturers' approval.
It is recommended that all EIFS systems should be 3/8-inch to 1/2-inch from protrusions to allocate the application of a properly sealed isolation joint. The use of backer rod is recommended to prevent three-sided adhesion failure.
Poor Workmanship
Thin base coat. Ensure that the thickness of the base coat is it a minimum of 3/32 inches (or 2.4mm), and apply it in two layers with at least 24 hours between these applications. If a cementitious base coat is used apply a primer (Kenney & Piper, 2).
Exposed mesh. Offset laps in mesh. Use diagonal mesh at reentrant corners. Fully embed mesh, leaving no mesh visible. Use high-impact resistant mesh in surfaces that may face additional wear and tear.
Sealant failures. Provide joint widths that can accomodate expected movements. Provide smooth primed surfaces free of mesh where sealant is to be placed. Apply sealant to base coats only and make sure that joints are tooled prior to finishing.
V-groove cracks. Rounded grooves are preferable to V-grooves.
Cracks at openings. Board joints shall not align with door and window openings and V-grooves.
Board joint cracks. Ensure that decorative grooves and V-grooves do not align with board joints. Board joints shall be offset from sheathing joints and openings.
Conclusion
Drainage EIFS systems were initially seen as the answer, resolving most problems that occur. However , these systems do not keep all water out; rather they provide a drainage plane for the trapped water to leave the system. This may lead to reported problems because if and when the vapor barrier or moisture retarder fails moisture will enter through the building envelope.
However, it should be noted that with each new building code that comes out energy standards are increased; leading to higher insulation needs. ASHRAE is the basis for many U.S. building codes and since 2007 has mandated the use of continuous insulation. Figure 9 below is a great example of EIFS successfully installed.
Figure 9 shows a building that used EIFS for its flexibility and aesthetic appeal(Photo Credit: ian m. at Flickr.com)
Bibliography
Bomberg, M., K. Kumaran, and K. Day. (October 01, 1999) "Moisture Management of EIFS Walls-- Part 2: Classification of EIFS Systems." Journal of Building Physics, Vol. 23. 159-172. < http://jen.sagepub.com/content/23/2/159> This paper outlines and describes five different moisture management strategies for EIFS. The basis of this research was done to improve the relationship between design practice and climatic conditions for wall moisture protection.
Bomberg, M. T., J. W. Lstiburek, and F. Nabhan. (January 01, 1997). "Long-term, Hygrothermal Performance of Exterior Insulation and Finish Systems (EIFS)." Journal of Thermal Insulation and Building Envelopes, Vol. 20. 227-248. This paper is divided into three parts: 1. the assessment of materials of EIFS; characterizing their hygrothermal performance, 2. development of a new test for evaluating EIFS integrity under simulated climatic cycling, and 3. recommendations for EIFS design solutions and construction details for new and retrofit construction.
Boyd, Jon M. and Scheffler, Michael J. (June 1999). “Water Problems in Building Exterior Walls: Evaluation, Prevention, and Repair.” Symposium Atlanta, Georgia. (April 18-19, 1998). The papers in this symposium are presented to expand the understanding of water behavior in building wall systems. Some specific case studies are looked at to provide practical and informative insight.
Cheple, Marilou, M.S., and Patrick H. Huelman, M.S. (February 15, 2000). “Literature Review of Exterior Insulation Finish Systems and Stucco Finishes.” Cold Climate Housing Program, University of Minnesota. This document reviews literature and research related to water intrusion in EIFS and stucco systems. Most of the research in the paper addresses problem identification and remediation.
Dow Corning. “EIFS Restoration Guide.” This bulletin provides installation and field testing instructions for Dow Corning brand sealants, coatings, and primers for EIFS applications.
EIMA - EIFS Industry Members Association. EIFS - Engineered for Performance. Designed to Inspire. N.p.: n.p., 2012. Print. This packet of information provides current information pertaining to EIFS and industry related news.
Friedman, Daniel. InspectAPedia. Oct.-Nov. 2012. Email. This information was personal information and opinions provided to me by a representative working for InspectAPedia.com
Hall, N., Ph.D., P.E., A.I.A. “Exterior Insulation and Finish Systems.” This paper provides insight into EIFS systems by defining the types, addressing common problems, identifying industry groups, and outlining current news topics.
Keclik, Gary B. and Maino, Amanda L.(2008). "Lessons learned for exterior insulation finish systems.”AEI 2008: Building Integration Solutions. <http://dx.doi.org.ezaccess.libraries.psu.edu/10.1061/41002(328)49>
This presentation, later turned into a paper, showcases an EIFS failure that highlights many common deficiencies that lead to damage.
Kumaran, M. K., and A. N. Karagiozis. (1998). "Drying Potential of EIFS Walls: Innovative Vapor Control Strategies." International Council for Building, Vol. 213. 493-509. This paper presents a study to determine the drying potential of EIFS systems. Three vapor control strategies were use to investigate the systems’ hygrothermic performance characteristics.
Lampo, Richard G., and Johnathon C. Trovillion. (1990). "Exterior Insulation and Finish Systems (EIFS) on U.S. Army Facilities: Lessons Learned." Construction Engineering Research Laboratory. (October 1990). This report outlines problems typically found with EIFS, and recommendations for preventing and correcting such problems in new and existing buildings.
Lucuik, M. (2007). “Estimating the Environmental Consequences of Building Envelope Failures.” ASHRAE Buildings X Conference. <http://www.ornl.gov/sci/buildings/2012/Session%20PDFs/238_New.pdf > This paper demonstrates the embodied effects related to premature building envelope failures and how they can be estimated. These failures are then made relevant to other environmental effects.
Nelson, Peter E., and Richard E. Kroll. (1996). Exterior Insulation Finish Systems (EIFS): Materials, Properties, and Performance. West Conshohocken, PA: ASTM, (December 1996). Print. This is the second international symposium that presents recommended changes, improvements, and refinements of existing concepts used with EIFS systems.
Piper, R., and R. Kenney. (1992). "EIFS Performance Review." Journal of Light Construction. This paper provides installation tips and techniques that should mitigate the occurrence of common problems found in EIFS.
Thomas, Robert G. (1992). Exterior Insulation and Finish System Design Handbook. Vashon Island, WA. CMD Associates. Print. This book provides basic, independent technical information about EIFS. It goes as far as to point out what works and what does not.
Williams, Mark F,, and R. Lampo. (1995). Development, Use, and Performance of Exterior Insulation and Finish Systems (EIFS). Philadelphia, PA: ASTM. Print. In this publication, 28 papers are presented addressing EIFS. The papers have been divided into six main categories: history, material and system performance, standards and building codes, maintenance and retrofit use, sealant joints, and new material and system developments.
EIMA: EIFS Industry Members Association. "Working toward the Advancement of EIFS." <http://www.eima.com/> This website provides technical documents, educational programs, and other pertinent information about EIFS being used in the industry.
Image Sources
Images from InspectAPedia.com and all other sites are used with permission. o I have emailed a few organizations about gaining permission to use their graphic.
Logan Gray, LEED Green Associate, BAE/MAE Architectural Engineering, The Pennsylvania State University, 2012
Table of Contents
Introduction
(Photo Credit: InspectAPedia.com)
The damage from these failures can be minor or catastrophic, costing an unprecedented amount of money to fix each year. Research has led to refinements in the types and techniques used for installation and maintenance of an EIFS, which can greatly improve the performance characteristics; limiting failures and reoccurring problems. The most predominantly used EIFS system currently in the industry is EIFS with Drainage.
Exterior Insulation Finish Systems (EIFS)
EIFS are synthetic stucco exterior cladding systems that are composed of one layer of exterior insulation board with two coats of finish. EIFS are designed as a barrier type wall system, which means that the insulation within the system is attached directly to the structure of the wall. Unlike traditional cladding like concrete, brick, and glass, EIFS components are proprietary and have a relatively short history within their respective industry. For these reasons, the installation procedures, sequencing and methods may also vary between manufacturers. If materials are not compatible and apt for installation, poor performance may result.This exterior building system, if installed properly and if no damage occurs to it, creates a water-tight skin that is essentially leak proof for the life of the structure. Otherwise, when leaks occur, water becomes trapped within leading to severe insect damage, rot, and mold problems. Assuming that the building envelope will remain undamaged, whether it be from impacts or improper installation, over its lifetime is a fallacy and should never be expected (Friedman, 2012).
Components of the system are explained in detail below and these components can be seen in Figure 2:
Origin of EIFS
This system was first developed in Europe after the Second World War to accommodate immediate reconstruction of war tattered cities. When energy sources became limited, retrofitted wall systems that could improve insulation properties of existing walls led to the development of EIFS. Early studies indicated that using 2 - 4 inches of external insulation was estimated to provide 30 percent more energy efficiency than a similar amount of insulation placed within a wall. In addition to energy bills being lowered, placing insulation on the exterior of a building reduced temperature differences between the habitable interior and the exterior. This lowered temperature differential reduced the tendency for components to move, crack, and offered lanes for moisture to penetrate through the building envelope. Because of its ease of installation and flexibility it became a popular product for exterior retrofits.The system eventually spread across the Atlantic and the first use of EIFS in the United States was in 1969 by Dryvit System (Hall, 1). Dryvit and their competitors focused efforts on the commercial building market sector through the 70's and into the 80's. Then, companies began to implement this system in the residential market. By 1994, 35% of new homes were being clad with EIFS (Hall, 3). The first identifiable problem in the thriving market was due to quality control problems.
One testing and evaluation study was performed by an American Institute of Architects (AIA) Task Force in Wilmington, North Carolina in 1995. 2,009 homes were inspected which involved 19 different builders and 12 different EIFS manufactured systems. Of those inspected 68% had improper or no sealant joints and 94% suffered from some degree of water intrusion. The cause of the problem was determined to be an inadequate design and poor water management details that had no drainage plane for water that enters the system. A lawsuit was filed against the manufacturers and some of the major installers; most leading to settlements (Hall, 3).
With over a billion square feet installed and a high degree of acceptance it is likely that the relatively new system has been under close scrutiny (Lampo and Williams, 11, 1995). With less than 50 years of existence in the United States there has still been sufficient evidence that the characteristics of EIFS -- flexibility, versatility, light-weight, and low-cost -- will continue to be valuable assets as we proceed though the 21st century.
Properties of EIFS
- Light weight
- Aesthetic appeal (including multiple colors and textures)
- Substantial insulation properties
- Retro-fitting capabilities
- Low cost
- Exterior installation
- Minimal thermal bridging
- Versatile Design
Figure 3 to the right shows EIFS in its various stages of application.EIFS System Types
The first type of EIFS developed (known as Barrier EIFS) consisted of an insulation board fastened to a substrate, glass fiber reinforcing mesh, a base coat that also acted as a weather barrier on the face of the insulation, and a textured protective finish. In response to the large number of water penetration failures occurring behind the weather barrier a second generation of EIFS was developed -- EIFS with Drainage.The following EIFS systems are the six basic types as found in Hall, 1-2:
Common Problems
There are typically a staggering number of problems in a building, but the ones that cause most concerns usually result in aesthetic or structural damage. For exterior insulation finish systems most performance issues are found when a thorough investigation of the skin of the building is carried out. It is easy to point out problems by simply making notes of any obvious water infiltration points or possible future infiltration locations - usually cracks or deteriorated joints.Unlike most other rain screen cladding systems, most barrier EIFS system types do not provide a capillary break or a drained cavity. Therefore, imperfections and even planned penetration locations in the surface, leaves EIFS susceptible to multiple moisture problems. In the following sections, commonly found problems will be pointed out and explained.
Cracking
Some failures, like delamination of the finish coat, can be caused by the wetting of the finish coat. There have been cases where the finish coat had been pulled off by accumulated ice adhered to the surface. There are also documented cases where the insulation behind the finish coat, and the backer rod behind the sealant, were saturated. Where snow was found in prolonged contact with EIFS surfaces, delamination of the finish coat was commonly observed (Nelson & Kroll, 15, 1996).
Moisture Penetration (aka Water Intrusion)
The four most predominant moisture transport mechanisms are (Hall, 6):
- Liquid Flow. This type of movement is the direct influence of a driving force such as gravity, surface tension, or air pressure differentials. These forces push water through openings in the envelope.
- Capillary Action. This occurs as a result of moisture movement through porous materials.
- Air Movement. An air pressure differential paired with drives moisture through the assembly.
- Vapor Diffusion. This is the movement of moisture in its vapor state through a material.
In one instance, water entered an unfinished joint, traveled through the insulation, and leaked into the interior causing extensive drywall and carpet damage (Nelson & Kroll, 15, 1996).The space behind the EIFS may be a place where water becomes trapped because after water enters the space it is unable to escape. The vapor impermeable materials that reside on both sides of the space eliminate the chance of evaporation and drying.
The Wisconsin Department of Health has issued a health advisory connecting EIFS as a source of indoor mold infestation and mold-induced illness (Hall 7).
Impact
The material may look like concrete, stone, stucco, and other similar materials, but EIFS have a relatively low tolerance for impact. It is common to see additional reinforcing mesh on places that are subject to damage. Areas near grade have been found most often documented as the places where damage occurs. Other documented impact damage includes damage from window washing stages, falling objects, shopping carts, etc. Figure 6 shows an example of impact damage to EIFS.
More often than not, this particular problem does not originate from the EIFS, but from faulty windows, open sealant joints, lack of knock-out flashing, and loose and improperly installed flashing. Figure 7 is an example of improperly installed flashing at a roof/wall junction that led to the presence of water and serious leaking within the walls of the home.
Substrates are not typically marketed or supplied by EIFS manufacturers and selection guidelines are of very limited. Design professionals are responsible for the selection and installation requirements of the substrate, including the way in which it is attached. Specification requirements for fastener type and spacings to attach the substrate must be based on structural design loads. Failure to attach the substrate adequately can lead to the substrate being blown off the side of buildings.
Sealant Failures
Joint sealant is not commonly supplied by EIFS manufacturers, but its installation and performance are vital to the success of the system. As mentioned above, most water intrusion failures are caused by either the absence of sealants or improper application of sealants. Sealant failures include tears, uncured sealant, and other defects not unique to EIFS joints and can be found in many cladding systems.
The four types of sealant failures that follow are those that are most commonly found:
Poor Workmanship
Case Studies
A 34,600 square foot three building complex located in northern California (Maino & Keclik, 1)All three building were single-story wood framed structures on shallow concrete foundations with slab-on-grade floors. The building envelope consisted of wood stud walls covered with 3/8-inch plywood sheathing, glass fiber faced gypsum wall board, and EIFS. The EIFS was made up of a 4-inch expanded polystyrene (EPS) insulation adhered to the gypsum wall board, which was anchored to the underlying wood framing. The EPS was covered with a thin polymer based (PB) coating, the thickness of the PB was dependent on the risk of impact. The joints between the EIFS and the fenestration units were sealed to the EIFS finish coat with a urethane-based sealant. To accomplish an accurate assessment of the building, the company conducted interior and exterior surveys as well as water testing and destructive openings at representative locations.
The main observations of the survey revealed, but were not limited to:
It was concluded that the EIFS system could have performed properly if attention to manufacturer and industry standards had been followed. The major cause of water intrusion on the building was the lack of attention to important details, such as window-to-EIFS interfaces.
Exterior Insulation and Finish Systems on U.S. Army Facilities (Lampo & Trovillion, 7).
Army facilities have increased the use of EIFS because of the cost effectiveness, insulation efficiency, and low-maintenance finish. Several failure types have been identified, such as delamination and extensive cracking typically caused by design and/or installation deficiencies. The report provides an analysis of four main problem areas: 1. mechanical damage, 2. system cracking, 3. design issues, and 4. construction deficiencies. It was found that most problems were minor, and that most, if not all, could have been prevented or corrected by relatively simple maintenance and repair procedures. Recommendations are made at the end of the report to help prevent the four main problem areas explored.
EIFS Training and Inspection Programs
There are a number of different training and inspection programs that have been developed to help educate those working with EIFS. A few example follow:Course Topics Include:
2. EIFSMART Contractor.
The purpose of a visual inspection is to is to detect any potential problem area, which may permit water leakage and consequential damage. The inspector should develop a comprehensive checklist to check for:
The Future of EIFS
Since its introduction into the indursty more than 40 years ago, many improvements have been made to EIFS, including:EIFS Claims History
The litigation and claims history of EIFS has decreased considerably over recent years. A study by EIFS Industry Members Association (EIMA) has shown a steady decline in the number of claims brought against four major EIFS manufacturers.Prevention/Solutions
There are a considerable amount of failure modes that exist for an EIFS. With the help of research and failure assessments solutions have been developed to improve the durability and longevity of the systems. Most solutions are preventative means and methods recommendations that should be introduced during design and construction.Condensation
If the material that supports the insulation can be damaged by moisture, the EIFS insulation thickness should be substantial enough to eliminate the possibility of the interior air reaching the dew point. The most extreme winter conditions should be used in the formulation of the insulation thickness.
Impact Resistance
To improve impact resistance performance companies have developed a high impact mesh. This heavy mesh does provide additional resistance, but has proven to be inadequate for areas that are prone to severe and continuous impacts.
Substrate Problems
Gypsum sheathing is extremely vulnerable to water damage when cracks and sealant failures are present. Even if extreme caution is taken to protect the gypsum board from exterior water penetration, condensation, and interior flooding the chances of providing a perfect seal are very slim. Because cracks and moisture intrusion is inevitable with an EIFS it is recommended to avoid the use of gypsum as a substrate.
Sealant Failures
Before a sealant is specified the sealant and EIFS manufacturers should be consulted and compatibility should be assured in order to ensure a successful system.
Proper joint geometry, which includes bond breaker materials, is a necessary material for failure prevention. The use of open-cell backer rod is not recommended because of its tendency to transfer and hold moisture. Bonding surfaces shall be prepared with manufacturers' approval.
It is recommended that all EIFS systems should be 3/8-inch to 1/2-inch from protrusions to allocate the application of a properly sealed isolation joint. The use of backer rod is recommended to prevent three-sided adhesion failure.
Poor Workmanship
Conclusion
Drainage EIFS systems were initially seen as the answer, resolving most problems that occur. However , these systems do not keep all water out; rather they provide a drainage plane for the trapped water to leave the system. This may lead to reported problems because if and when the vapor barrier or moisture retarder fails moisture will enter through the building envelope.However, it should be noted that with each new building code that comes out energy standards are increased; leading to higher insulation needs. ASHRAE is the basis for many U.S. building codes and since 2007 has mandated the use of continuous insulation. Figure 9 below is a great example of EIFS successfully installed.
Bibliography
Bomberg, M., K. Kumaran, and K. Day. (October 01, 1999) "Moisture Management of EIFS Walls-- Part 2: Classification of EIFS Systems." Journal of Building Physics, Vol. 23. 159-172. < http://jen.sagepub.com/content/23/2/159>
This paper outlines and describes five different moisture management strategies for EIFS. The basis of this research was done to improve the relationship between design practice and climatic conditions for wall moisture protection.
Bomberg, M. T., J. W. Lstiburek, and F. Nabhan. (January 01, 1997). "Long-term, Hygrothermal Performance of Exterior Insulation and Finish Systems (EIFS)." Journal of Thermal Insulation and Building Envelopes, Vol. 20. 227-248.
This paper is divided into three parts: 1. the assessment of materials of EIFS; characterizing their hygrothermal performance, 2. development of a new test for evaluating EIFS integrity under simulated climatic cycling, and 3. recommendations for EIFS design solutions and construction details for new and retrofit construction.
Boyd, Jon M. and Scheffler, Michael J. (June 1999). “Water Problems in Building Exterior Walls: Evaluation, Prevention, and Repair.” Symposium Atlanta, Georgia. (April 18-19, 1998).
The papers in this symposium are presented to expand the understanding of water behavior in building wall systems. Some specific case studies are looked at to provide practical and informative insight.
Cheple, Marilou, M.S., and Patrick H. Huelman, M.S. (February 15, 2000). “Literature Review of Exterior Insulation Finish Systems and Stucco Finishes.” Cold Climate Housing Program, University of Minnesota.
This document reviews literature and research related to water intrusion in EIFS and stucco systems. Most of the research in the paper addresses problem identification and remediation.
Dow Corning. “EIFS Restoration Guide.”
This bulletin provides installation and field testing instructions for Dow Corning brand sealants, coatings, and primers for EIFS applications.
EIMA - EIFS Industry Members Association. EIFS - Engineered for Performance. Designed to Inspire. N.p.: n.p., 2012. Print.
This packet of information provides current information pertaining to EIFS and industry related news.
Friedman, Daniel. InspectAPedia. Oct.-Nov. 2012. Email.
This information was personal information and opinions provided to me by a representative working for InspectAPedia.com
Hall, N., Ph.D., P.E., A.I.A. “Exterior Insulation and Finish Systems.”
This paper provides insight into EIFS systems by defining the types, addressing common problems, identifying industry groups, and outlining current news topics.
Keclik, Gary B. and Maino, Amanda L. (2008). "Lessons learned for exterior insulation finish systems.” AEI 2008: Building Integration Solutions. <http://dx.doi.org.ezaccess.libraries.psu.edu/10.1061/41002(328)49>
This presentation, later turned into a paper, showcases an EIFS failure that highlights many common deficiencies that lead to damage.
Kumaran, M. K., and A. N. Karagiozis. (1998). "Drying Potential of EIFS Walls: Innovative Vapor Control Strategies." International Council for Building, Vol. 213. 493-509.
This paper presents a study to determine the drying potential of EIFS systems. Three vapor control strategies were use to investigate the systems’ hygrothermic performance characteristics.
Lampo, Richard G., and Johnathon C. Trovillion. (1990). "Exterior Insulation and Finish Systems (EIFS) on U.S. Army Facilities: Lessons Learned." Construction Engineering Research Laboratory. (October 1990).
This report outlines problems typically found with EIFS, and recommendations for preventing and correcting such problems in new and existing buildings.
Lucuik, M. (2007). “Estimating the Environmental Consequences of Building Envelope Failures.” ASHRAE Buildings X Conference. <http://www.ornl.gov/sci/buildings/2012/Session%20PDFs/238_New.pdf >
This paper demonstrates the embodied effects related to premature building envelope failures and how they can be estimated. These failures are then made relevant to other environmental effects.
Nelson, Peter E., and Richard E. Kroll. (1996). Exterior Insulation Finish Systems (EIFS): Materials, Properties, and Performance. West Conshohocken, PA: ASTM, (December 1996). Print.
This is the second international symposium that presents recommended changes, improvements, and refinements of existing concepts used with EIFS systems.
Piper, R., and R. Kenney. (1992). "EIFS Performance Review." Journal of Light Construction.
This paper provides installation tips and techniques that should mitigate the occurrence of common problems found in EIFS.
Thomas, Robert G. (1992). Exterior Insulation and Finish System Design Handbook. Vashon Island, WA. CMD Associates. Print.
This book provides basic, independent technical information about EIFS. It goes as far as to point out what works and what does not.
Williams, Mark F,, and R. Lampo. (1995). Development, Use, and Performance of Exterior Insulation and Finish Systems (EIFS). Philadelphia, PA: ASTM. Print.
In this publication, 28 papers are presented addressing EIFS. The papers have been divided into six main categories: history, material and system performance, standards and building codes, maintenance and retrofit use, sealant joints, and new material and system developments.
Additional Resources
Wikimedia Foundation. "Exterior Insulation Finishing System." <http://en.wikipedia.org/wiki/Exterior_insulation_finishing_system>.
This website provides basic terminology and information about EIFS.
EIMA: EIFS Industry Members Association. "Working toward the Advancement of EIFS." <http://www.eima.com/>
This website provides technical documents, educational programs, and other pertinent information about EIFS being used in the industry.
Image Sources
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