Exterior Insulation and Finish Systems (EIFS)
3/30/1999

Synthetic Stucco Update

Exterior Insulation and Finish Systems (EIFS- pronounced "eeefs"), sometimes referred to as "synthetic stucco" is a relatively new exterior cladding that has appeared in the residential real estate market in the last ten to fifteen years. Although it is similar in appearance to hard coat stucco it is worlds apart in concept and application. Hard coat stucco has been around for several thousand years and has stood the test of time. EIFS has been around for less than 50 years (about 30 in the USA) and its future in the residential market is uncertain. Designed to be a versatile, monolithic, weathertight, exterior insulation system, EIFS wraps the house in a lightweight, energy-efficient thermal and moisture blanket. EIFS by design is a seamless face-sealed "barrier system" designed not to let air or moisture pass through it and has been very successful in doing so. Its success may be its biggest problem! It is a highly effective "shrink wrap". All other exterior claddings on residential properties "breath" allowing the free movement of moisture and air. Serious problems have occurred with EIFS when moisture gets behind the exterior surface; it gets trapped in the wall cavity causing wood rot (wood begins to rot when it reaches or exceeds 20% moisture content) and makes the wood very prone to insect infestation. This has created concerns with homeowners and builders nationwide. Over the past two years "drainable" EIFS systems have been introduced by two EIFS manufacturers to overcome moisture problems. More about that later!

Let’s look at the original residential EIFS system. Please keep in mind that there are hybrids of the EIFS system listed below, however, the system described is the most common in the marketplace. EIFS is an exterior cladding system comprised of 2’ x 4’ insulation boards, a glass fiber mesh, a weatherproof base coat and a finish coat. The insulation board is expanded polystyrene insulation (EPS) which can vary in thickness from 3/4" to 4" ( most residential installations are 3/4" to 2" in thickness). This is affixed to the wall sheathing (usually plywood or oriented strand board -OSB) with an adhesive. A plastic coated glass reinforcing mesh is embedded into a trowelled-on resinous base coat. Lastly an acrylic finish coat with intregal color and texture (aggregate additive) is trowelled or sprayed on. The face coat gives it the monolithic "stucco" look. The finished product is lightweight, very energy efficient, and waterproof. It can be detailed (because of the insulation board) into many different shapes and styles and it is also easy to repair if damaged.

Because EIFS is a "system" no installation is considered complete without attention to expansion joints, caulking, sealants and flashing where EIFS meet dissimilar materials such as doors, windows, roofs, & other wall claddings. Penetrations such as plumbing and utility outlets also need to be addressed. The majority of EIFS homes that do experience moisture problems normally do not have proper caulking, sealant or flashings where the EIFS is terminated or penetrated and moisture leaks in around the edges of the EIFS. Even if the EIFS is properly caulked and sealed wood trim around doors or windows can allow moisture behind it and thus behind the EIFS.

EIFS was first used in Europe after WW II to meet post war reconstruction demands. Installed over masonry substrates it worked very well and still does. In the early 70’s it was brought to the United States for use on commercial buildings with a great deal of success, and is still widely used for that purpose. Today many motels, fast food restaurants, office buildings, retail strip centers, apartments & condominiums are partially or fully cladded with EIFS.

In the residential market EIFS is usually found on up-scale custom homes built after the mid-to late 80’s and has been used either as an accent material with other exterior claddings, such as brick, stone, wood siding, or fully sided with EIFS. It is an extremely versatile product, and architects love it because they can create very decorative features at prices competitive or cheaper than brick or stone. EIFS homes can be very stunning and architecturally pleasing - lots of "curb appeal". Thousands of homes have been built with EIFS since the mid-80’s, and almost all of them are barrier systems applications. EIFS is found in all 50 states and many up-scale homes built in the last 10-15 years that have a stucco appearance are cladded with EIFS. The most notable exception is the southwestern part of the United States where hard coat stucco is still common on "Spanish style" homes.

The majority of EIFS construction is on commercial buildings which are normally build with masonry and not as susceptible to moisture damage as wood framed structures. However, residential construction is almost always "stick built" and serious problems have developed. Most exterior sidings will telegraph moisture problems. Not so with EIFS! If moisture does get behind the EIFS it is trapped and can rot the wood sheathing and framing leaving the EIFS untouched, maintaining its excellent external appearance with no indication of damage to the wall cavity underneath. The damage is concealed. Because it does not breath the damage can occur quickly - often within several months after construction is completed. EIFS is not forgiving when improperly installed or if leaks develop at penetrations. By the time problems surface it is usually after considerable damage has already occurred. Unfortunately an alarming number of EIFS failures have occurred and the number of failures seems to be increasing.

The extent of the problem first came to the public’s attention in Wilmington, NC in 1995 when numerous homeowners began experiencing problems which ultimately resulted in a class action lawsuit in North Carolina. Since 1995 the number of homes and the location of homes experiencing problems has spread nationwide. Problems have occurred in all 50 states and appears to be snowballing. The National Association of Home Builders (NAHB) Research Center began suggesting all homes with EIFS be tested for moisture after the North Carolina Builders Association came up with 75% of randomly tested homes having some degree of damage, with average repair costs between $3,000 and $5,000. Several builders have reported repair costs as high as $100,000, with one insurance settlement at $417,000. The American Institute of Architects (AIA) found high moisture levels in 90% of some 205 EIFS houses tested. North Carolina and Georgia Building Officials have banned barrier EIFS systems and the Maryland Casualty Company (one of the largest insurers of home builders in the nation) now excludes coverage for houses containing EIFS.

The National Pest Control Association (NPCA) in May of 1998 issued a statement to its members recommending Pest Control Operators (PCOs) not attempt to treat EIFS homes with termiticides if the insulation extends to the soil as it is "untreatable". NPCA recommends an 8 inch "clear barrier" between the ground and the lowest level of EIFS. NPCA also recommends PCOs exclude or disclaim EIFS structures from warranties and contracts as they are impossible to inspect for insect or wood rot damage without destructive testing. Termites and carpenter ants love to tunnel through the insulation board as they travel from the ground to the building and back again. NPCA and NAHB both recommend moisture intrusion tests on all EIFS homes. The International Code Council (ICC) in its 1998 International One and Two Family Dwelling Code has also banned the use of "rigid foam" (which includes EIFS insulation) insulation below grade in areas of "very heavy" termite infestation. Very heavy termite areas include California, the gulf coast states, and the southeastern states of Georgia and South Carolina.

Testing consists of a three-step approach:

1. Inspection. A visual inspection of the house to see if the installation was to industry standards and to note any deficiencies.

2. Scanning & Probing. A wet wall detector is used to scan the wall. Areas that read high are probed to the substrate and/or framing with a moisture meter to obtain moisture readings of the wood sheathing and members.

3. Reporting. Report findings in writing detailing locations with high readings by photos and/or drawings.

Areas that register high readings (over 20%) require destructive testing by removing the EIFS to visually inspect the underlying sheathing and stud walls with repairs made as needed.

Because of the above problems two of the major EIFS manufacturers have gone to "water management" systems and away from the "barrier" systems on all residential and commercial installations claiming face-sealed barrier systems are incompatible with normal construction practices. Both have stated that "it is impossible to design and build a face-sealed barrier structure that will not leak". "Water intrusion is a normal occurrence in residential construction and is not a function of quality of construction". Indeed, independent research dating back to the mid-60’s has repeatedly shown that it is simply impossible to make a home water-tight. Both manufacturers now recommend a back-up redundant system, a weather-resistant barrier, which also functions as a drainage plane.

It now appears that other EIFS manufacturers are beginning to offer drainage systems as part of their residential products, but with a lot less fanfare. The EIFS Industry Members Association (EIMA) in late 1998 announced it now recommends the use of "drainage" or "water managed" EIFS for one and two family residential construction while still offering "barrier systems". In fact in January 1999 one of the largest manufacturers of EIFS very quietly changed their web site to show "moisture drainage" systems as their standard residential product, removing the original "barrier system" from its web page. Because drainage systems (or hybrid systems) are so new they are literally being field tested on peoples homes with very little research. In theory they should work but there has been no long term testing.

It appears the EIFS manufacturers may have been too successful with their product. It usually doesn’t leak on the face, in most cases it leaks around the edges. With the media attention EIFS homes are becoming "stigmatized" and difficult to sell in some parts of the country. Purchasing a home with EIFS warrants some research and relocation professionals should be aware of its presence and have a policy in place to deal with it.