Exterior Finished Systems
EIFS (“Exterior Insulated Finish Systems”) is an exterior wall cladding system also known as “synthetic stucco.” (photos bottom of page)
Older EIFS systems developed water entrapment problems resulting from installation (rather than product) deficiencies. More recent EIFS wall systems, generally installed in 2004 or later, generally have eliminated or materially mitigated water entrapment problems by including drainage.
EIFS installation are categorized broadly into two separate periods.
They are the more modern drainage type systems (“EIFS with drainage”) and the predecessor, usually pre-2004, (“nondrainable” or PM/PB) barrier type systems.
Today, practically all of the EIFS market is dominated by drainage systems.
As a practical matter, older barrier type systems are largely legacy systems in residential construction, since adoption of the 2004 updated standards for EIFS in 2004.
In the residential (wood, light frame) installations, nondrainable systems are discussed because of the problems that developed with them and because the pre-2004 systems are still out there, and too many have problems. (Some barrier systems are still applied commercially, but typically that’s concrete and steel frame buildings.)
The key feature of “EIFS with drainage” is a water-resistant barrier behind the EIFS cladding, protecting the wood framing. Then discharge sites /”guttering” are installed to discharge incidental water that gets behind the insulation board.
That prevents the old problems of water entrapment in pre-2004 EIFS by supplying a the drainage path for moisture exists behind the EIFS to drain water to the exterior. The earlier, typically pre-2004 problems with water entrapment behind EIFS siding predominately resulted from flashing failures at penetrations, like windows, but also from vapor permeating the insulation.
While all manufactures say “EIFS with drainage” is not meant to accommodate rainwater that penetrates through other components of construction, such as flashing, there is no question that “EIFS with drainage” provides evacuation for that moisture. Indeed, that water evacuation was a primary reason for adopting the standard. (Of course, flashing is required where rainwater may penetrate other components and at the interface of different components, as always.)
Today, all EIFS manufacturers installing in North America “recommend” the use of water-resistive barriers over moisture sensitive substrates to provide additional protection in the event of a component failure.
State building codes basically require them too. State construction codes are not uniform. There is no nation-wide building code in the U.S., though the International Code Council (ICC) promulgates a model “International Residential Code” (IRC) which is the basis of building codes adopted in all 50 U.S. states today.
On this point, the 2006 ICC national model in effect today, as well as the version Kentucky adopted, basically defaults to manufacturers “installation instructions.” (IRC R703.9.)
However, the IRC and Kentucky expressly requires a water-resistive barrier between “water-sensitive building components” and the exterior insulation. A means of drainage also was added.
IRC 703.9 further requires a 6-inch ground clearance. Termination at or near grade have been a constant source of water intrusion complications, particularly with older barrier systems, though drainage systems are not immune.
Every three years, the ICC updates the national model IRC. Most states update their building codes in similar cycles, and all update every 5 or 6 years, a date arriving as this was being written. The 2012 IRC will be adopted in most states by January, 2013. Kentucky is expected to complete adoption of the 2012 building code in December, 2012 or January, 2013.
In this year’s ICC process, a change that would supply ways to measure drainage (FS 145), in addition to requiring drainage, was proposed but not approved (EIMA, the EIFS Industry Manufacturers Association, opposed it).
Finally, the legal liability of builders and sub-contracting installers has significantly affected installation standards of practice and duties of care. We discuss cases and laws separately, although inquiries always are welcome. Just email firstname.lastname@example.org or email@example.com.
The Oak Ridge National Laboratory published a study on EIFS performance in 2006. For more information, go to https://buildingscience.com/documents/published-articles/pa-water-managed-wall-systems/view, the site of the study’s author, Achilles Karagiozis, Ph.D. at the Oak Ridge National Laboratory.
Details concerning the 2004 updated standards are mainly in ANSI and ASTM standards, such as ASTM E2273-03 and E2221-03; cross-reference E2570-07.
The top 5 EIFS producers account for about 90% of the US market. These producers include Dryvit Systems, STO Corp., BASF/Senergy, Master Wall, and Parex.
Exterior Finished Systems continued
It’s main problem is moisture entrapment, often as a result of installation (rather than product) failures. Generally, the problem is that water gets behind the EIFS cladding and cannot get out, so it begins to deteriorate the framing members and structure.
EIFS is designed to be a face-sealed barrier providing a waterproof membrane. All water must be shed at the outermost surface. Water entering behind the base coat can enter the wall cavity. For that reason, watertight sealing around all penetrations (windows, doors, outlets, pipes, etc.) is essential.
EIFS was developed in Europe after WWII. Dryvit System of Rhode Island imported EIFS in 1969. From 1969 to 1976, Dryvit was the only producer of EIFS stucco. From 1976 to 1990, use of EIFS stucco increased dramatically. EIFS rapidly migrated to residential exteriors, initially as accents and highlights. By 1990, another 20 manufacturers produced it. In 1980, EIFS stucco was less than 0.5% of residential applications. By 2000, EIFS reached 17% of the commercial wall market and 3.5% of the residential market, with growth increasing 12-18% per year in both sectors.
In 2004, the EIFS industry sold about 440 million square feet of finishes; in 2005, the total was up to 552 million square feet – growth of roughly 25%.
However, by 1997, some states banned use of EIFS because of moisture problems. With such rapid growth in the industry, many new manufacturers entered the market and then ran into a shortage of qualified installers. There have been numerous lawsuits over EIFS installations. New acceptance criteria for EIFS systems were promulgated March 1, 2004 by the International Code Council (http://www.iccsafe.org/Pages/default.aspx).
Experts can readily identify faulty EIFS installations using a Tramex Wet Wall Detector and follow-up probes. Repairs are not difficult, if moisture is caught in time, since an EIFS area with a defect can be patched in. If a penetrated EIFS system is left uncorrected over time, it may result in catastrophic failure at significant cost to cure.
It is difficult, if not impossible, for a home inspector to visually distinguish EIFS systems from other more recent variations, such as PB Systems (polymer based systems), XPS (extruded polystyrene foam systems), PM systems (polymer modified systems, using XPS foam insulation over different substrate), and hybrid systems(for example, a stucco system using EIFS lamina as a finish coat because of its color retention, ability to stretch, and barrier to leakage). Most of them are subject to the same issues.
Client’s getting into EIFS systems frequently are told of the system’s history and advised to (1) consider synthetic stucco systems with particular care; (2) call an expert before closing if any concern is even remotely apparent; (3) obtain as much information as possible about the wall system and its repair history from the seller in writing; and (4) constantly monitor the synthetic stucco for any signs of failure or movement.
EIFS is built in layers, the outside shedding moisture, the inside holding in heat. While all EIFS systems are alike in construction, there are two basic categories – “standard” and “ultrahigh impact.
The insulation layer is closet to the interior. It also provides reinforcement. The interior EIFS is insulation board made of either polystyrene or polyisocyanurate foam about 1″ to 4″ thick. It is secured to the exterior wall surface with a special adhesive and/or mechanical attachment. In recent years, it often is applied on top of Tyvec or similar insulating moisture barriers for wood frames, which helped prevent problems. Home inspectors cannot tell visually if this is the case.
Normally, an EIFS proprietary drainage board is applied outside the polystyrene. A second layer of fiberglass EIFS reinforcing mesh is applied with an EIFS base coat which embeds the mesh. Finally, the third layer is an exterior EIFS acrylic co-polymer finish coat (or “lamina”) that sheds water and protects both the interior layers and the building. It also is both colorfast and crack resistant – giving superior resistance to fasing, chalking and yellowing. Because it keeps its original appearance over time, EIFS offers both initial and life-cycle cost savings to owners. The layers rest on a vinyl drainage track.
At its base, EIFS systems should terminate a minimum of 8″ above finished grade either with back-wrapping that is EIFS sealed and caulked or back-wrapping with EIFS mesh and base coating into the foundation. Most EIFS applicators are sub-contractors, who leave the site before landscaping and finish work is done.
Be alert for landscaping that is too near, or even overlaps, EIFS at points. If there is no gap or too little gap between the EIFS and finish grade, it can permit wicking moisture in the foam, which invites termites. (Damp EIFS foam is like a Club Med for termites. Once termites move in, though, it’s impossible to treat.)
Flashings are needed to move water away from the structure. There should be diverter flashings installed where a roof intersects a vertical wall. Older diverter joints were soldered; modern ones are one-piece plastic units. The areas where gutters meet sidewalls are often a point of EIFS moisture penetration. Step flashing should extend at least 6″ above the roof and any cricket or chimney enclosure. Door, window and deck flashings also must be functioning. Even though flashing has been a requirement for years, too many builders incorrectly believed that stucco exteriors did not need them. They built structures that saved small amounts at high risk to the building.
Expansion joints are required at all floor lines, places where there is a change in substrate, areas with structural movement, and places where EIFS terminates against a different material, such as concrete block or plywood. These joints are sealed with EIFS approved sealants and must be properly caulked. In older installations, before silicone caulk was standard, caulking may be seen cracking or detaching today, which should be noted. (It often can be repaired with pre-cured silicone sealants, which do not require removal of the old sealant, which can damage an EIFS substrate.) In older installations, expansion joints generally were about 1/2″; more recent installations use 1″ expansion joints.
Always look for signs of compression or gaps in EIFS expansion joints. They show the siding, and often the building, are in motion and imply further evaluation for moisture problems is advisable.
Penetrations – especially windows and doors, but even pipes, fixtures, outlets, fasteners and other things attached to the cladding – are the major source of water intrusion for EIFS systems.
Always check exterior windows, doors, and their casings and frames (windows and doors in modern homes probably were bought as packaged units) – especially where the units are wood. Wood windows are much more vulnerable to water than aluminum or vinyl clad windows. Be sure to check lower corners for softness, especially where there’s fresh paint. Inspectors can use probes to check for damage too, as long as they’re not so enthusiastic they cause damage.
Look out for casement windows from the 1950s and 1960s; often they had single-glazed construction. They performed poorly, typically having water leakage and condensation problems. They should have been replaced in an EIFS house, but be sure. Storm windows and screens usually are a sign of single-glazed windows.
Water flowing into EIFS systems and walls from leaky windows or doors can produce significant unseen damage. Sills should be inclined away from the house, or water can table or pool at the sill and get wicked up into the window and its casing. Deterioration follows quickly. Windows installed backwards usually have a reverse sill slope.