Recently, I participated in a certification seminar in Chicago on exterior insulation finish systems. This seminar was developed by the Association of the Walls and Ceilings Industry to provide education for plastering mechanics, industry professionals and inspectors. Having gone into this adventure thinking I could probably teach the course, frankly I was surprised at the intensity of the two-day instruction that was capped by a 135-question test, with a mandatory passing rate of 86 percent.

Interestingly, one of the points of discussion at this seminar was EIFS with drainage. It was noted by both the facilitator and the textbook, that the first EIFS that incorporated the rainscreen principle and drainage were introduced in 1993. After pondering this statement for a moment, I was tempted to raise my hand and take exception to what I felt was a misstatement. But I bit my tongue and bided my time until lunch, when I mentioned to the facilitator, Kevin Day, that I knew of a project that precluded that timeframe by a good five years. Perhaps in a spirited moment of one-ups-manship, Kevin responded that he knew of a project that was actually completed in 1981 but did not elaborate.

Therefore, I cannot say with great certainty that the subject of this article is in fact the first EIFS with drainage installation. Of course, if there is anyone out there who would care to throw in on this subject, that is your prerogative but this is my story and it is my belief that this may be the first substantive EIFS project done with the redundancy of a drainage plane.

The project I know is a 17-story building in Minneapolis. Why do I know of it? It was the first project that struck a chord with me as a newbie at the Insul/Crete Co. back in 1988. That project was the Ebeneezer Park Senior Apartments, at 2700 Park Avenue.

Out of curiosity, I ventured over that way one day to see how the building was holding up. Aside from needing a good power washing, all of the expansion joints, flashings, control joints and seals around the windows were holding up fine.

Wait a minute, you might ask, control joints? Yes, this particular project is perhaps unique among all of us in the EIFS world, because this was not your conventional lick-and-stick EPS-type polymer-based installation that we normally equate with the acronym EIFS. This was a polymer-modified EIFS, which perhaps makes this story even more interesting, if not a true oddity. What makes it even more odd is that this particular project was a re-clad of one of those more conventional polymer-based systems.

The devil: still in the details

It is not my intention in writing this article to denigrate the contractors, the project designer or the original EIF system that was used on this project. They will remain nameless in this regard. Nor is it my intention to paint PM EIFS as superior to PB EIFS. There is, however, some conjecture between the parties I interviewed about whether the problems that arose could be attributed to the materials, the design or simply the way the installation was executed. However, it seems apparent that the original project was destined to have problems from the start.

When I heard that the project was originally panelized, that was all I really needed to know about what transpired next. For those of you that have been involved in these types of operations, you know that the engineering must be well thought out and the construction precise. Deviation from measurement tolerances in one location can additively lead to huge discrepancies in other locations.

For example, a 1/2-inch panel joint at the lowest elevation of a riser could easily turn into a 11⁄2 inch joint somewhere else on the elevation. On top of that, there is the sealant that is used to connect one adjacent panel to another. It would not take any stretch of the imagination to realize that these joints were probably one of several issues that may have plagued the original construction. To make matters worse, it has been noted by one account on this project, that the post tension floor slabs were offset by as much as a 1/2 inch between floors.

It should not seem unusual then, that soon after the building's opening in 1981, the tenants began to see and feel the effects of water intrusion issues. Testing by one account may have contributed to the issues as fire hoses were used to conduct water tests on the building envelope.

"We didn't want to commit the same mistakes," says Dave Wagner who was assigned by the architectural firm, BWBR, to manage the re-design of the exterior façade. Although recollections have now become a little fuzzy for Dave, who retired some years ago, he was insistent that the window installation was also called into question on the project.

"I'm certain that as part of the remediation, we had to pull the windows," Wagner says.

The redesign then included an integrated pan flashing that redirects incidental moisture from the windows to the exterior of the new cladding.

As to the old PB EIFS contributing to water issues on the project, the evidence seems less damning.

"I tore off some of the EIFS in the field of the panels," says Peter Harrison, former technical director at Insul/Crete (now with PareXLaHabra). "It was pristine between the windows."

Having now been in the plastering business as long as I have, I am always a little perturbed by the phraseology used to describe a building envelope failure. Inevitably, they are classified as a "cladding" failure, when in fact, there usually is a myriad of deficiencies that probably have contributed to the situation.

This point hit home with me on this project when I talked to the building property manager about the trauma the elderly people of this apartment complex had to endure in the rehabilitation of the building. Trying to explain to her who I was, she said that she didn't have any kind words for me if I represented the original cladding manufacturer. But once I expressed that I had actually worked for a company that helped resolve the problems, her demeanor completely changed to the positive. I guess it didn't really dawn on her that the EIFS was actually replaced with a similar product.

This is perplexing yet indicative of the perception problem that has dogged the EIFS industry in recent years. The problems seem to be everything but the EIFS, yet the focus seems to manifest on the product, because it is the largest visible component of the wall envelope.

Cookies and Construction

The logistics of tearing off the old EIFS from the 17-story structure and replacing it with a new EIFS proved to be distressing for both the seniors living in the complex and the contractors. Planning began in 1987 with the construction starting in 1988 and stretching through 1989. Because the damages extended to the inside of the wall plane, tenants had to be moved to other suites in the complex.

Because the original EIFS was adhesively attached, tearing it off compromised the exterior gypsum sheathing substrate. Subsequently, the old sheathing had to be removed and new sheathing had to be installed. Not an easy task for a job that was originally panelized on the ground then hoisted into place with cranes. This issue was resolved with the use of hex lifts, which were a somewhat new and novel innovation in wall cladding in 1988. Time on the lift equipment was divided between the general contracting crew and the plastering contractors, who shared in the responsibility of remediating the structure. The EIFS installation was partnered by two recognized plastering firms in the Twin Cities. These were Peterson Stucco (now known as Brian Peterson Stucco) and Conroy Brothers (now known as Olympic Wall Systems).

PM and PB Differences

According to then-Conroy Project Manager, Bob Hede, a water-resistive barrier consisting of No. 15 asphalt felt was installed over the new gypsum sheathing to positively shed incidental moisture behind the new EIFS. The weep system consisted of coil coated aluminum flashing at each floor line which integrated with a zinc stop bead used to terminate the EIFS. This termination is preferable because the mesh and thickness of basecoat of a PM system is not conducive to the practice of backwrapping, which is common in a PB installation. In conjunction, these components provided intermediate relief for incidental moisture at each level of the 17-story mid-rise building.

Another anomaly to its PB sibling, is the use of expanded extruded polystyrene (Styrofoam), sometimes referred to as XPS, in lieu of expanded polystyrene or what is known as EPS. Unlike EPS, which comes in 2-foot-by-4-foot board sizes and 1-pound nominal density, PM systems are installed over 2-pound density, 2-foot-by-8-foot boards. Occasionally, one will see more conventional 4-foot-by-8-foot sheet sizes but this is discouraged because of their difficulty in positioning and also because the larger size and density tends to be less dimensionally stable. In today's installation of PM systems, it is not unusual to leave out the XPS entirely, in favor of a higher density EPS, which pretty much assimilates the performance of XPS, often at a lower cost.

Because XPS is a higher density than EPS, it also does not lend itself well to adhesive attachment. This installation was no exception; the very nature of the PM installation procedure was actually advantageous in providing the redundancy of a drainage plane behind the EIFS. The 3/8-inch-by-3/8-inch vertical grooves on 4-inch centers were cut into the square edge 21⁄2-inch thick insulation board off site. The boards were then mechanically attached over the previously installed WRB and sheathing substrate into the light gauge metal framing with corrosion resistant screws and plastic disk washers.

Is it EIFS or Stucco?

Aside from the fact that they are both called EIFS, one can argue that there are more differences than similarities between PB and PM type systems. A PM system has more of the attributes of a hybrid stucco system than what we conventionally refer to as EIFS.

In a PB EIFS, the reinforcing mesh is laid onto the freshly troweled basecoat material, then embedded and suspended within the thickness of the coating. This is where a PB system derives its strength. More like a stucco installation, in a PM EIFS, the reinforcing mesh is attached directly to the surface of the insulation board, using the same fasteners used for the primary attachment of the system. In this capacity, the mesh is similar to the lath attachment in a stucco installation, in that it provides a mechanical key for the fresh basecoat. In fact, the composition of the basecoat is startlingly similar to that of a field mixed stucco, in that sand, cement and water are mixed proportionally with an acrylic modifier. What makes it much better than stucco, however, is the synergy of the component parts, which really deserves some discussion.

In an EIFS installation, the basecoat is buffered from the substrate by virtue of the thickness of the foam board. This is important to note because even though the foam board is restrained by adhesive or mechanical means, there still is movement concentrated at the board edges. Now, imagine all of those other foam boards in an EIFS installation butting into one another. Some means must be used to keep all of these seams mended together. This is managed by the resiliency of the polymer modified basecoat adhered to the foam board, which essentially holds the insulation layer together. The tensile and impact strength of the base coat is imparted by virtue of the reinforcing mesh.

Without going into too much detail (that's another article), a similar stucco installation over foam board does not offer the same synergistic attributes. Although it is a good product with its proper use, it is also thick and brittle and simply cannot accept the same stress transfer that EIFS can. This translates into unacceptable levels of cracking. Try as we may to convince people otherwise, we continue to see specifications that call for stucco over foam board in lieu of EIFS.

The Coupe Deville of EIFS

The polymer enhancement of modern EIFS basecoats provides the advantage of resiliency to thermal changes, moisture levels, structural loads, etc. In this respect, thinner is generally regarded to be better. As an elementary example, consider the elasticity of various sizes and thicknesses of rubber bands. Thin stretches more than thick.

A similar analogy can be applied to EIFS and stucco. Polymer-based EIFS requires little attention to the control of system design stresses. While in stucco, it is a familiar consideration to break a wall area into 144 square-foot panels with the aid of control joints. Although a polymer modified EIFS is thinner than stucco (1/4 inch to 3/8 inch vs. 3/4 inch to 7/8 inch) it also is governed by a similar set of rules. The consideration then for control joints must be carefully thought out based upon optimum function and aesthetics for the building.

In talking about PM systems, I can't help but remember how Insul/Crete saw its competition as PB-type EIFS. It was marketed as superior because of its thickness (1/4 inch vs. 3/32 inch), higher R-value (R5 vs. R3.6) with better impact resistance. Over time, we have come to accept these selling points as moot in the relative standing of these products but nonetheless we equated the products as the difference between a Cadillac (PM EIFS) and a Chevrolet (PB EIFS).

The problem we had was that while the PM system may have been the Cadillac, it was also as pricey as one and a bit of an albatross with respect to its thicker basecoat and complex installation procedure. Add to this the perception that more joints could mean more potential for water intrusion issues and you can understand why the PM system is not a widely accepted alternative to PB EIFS. Although most EIFS manufacturers maintain these products as part of their product line, they have fallen out of favor by architects and contractors alike.

Lessons learned

There does seem to be more than one lesson to be learned from this story. The first lesson is that there really is no "bad" EIFS. It would be bizarre for any EIFS manufacturer to market a product that was not effective. This project proves that theory in spades, in that two different EIFS were used at different times. The PB system, who's premier status has remained venerable over the years, and the other (PM), which has been relegated to EIFS' forgotten past. What seems ironic, however, is that the product that was used in the fix, with all of its inherent misgivings about control joints, mechanical attachment and thicker basecoat, was considered a success-which leads to lesson two, perhaps the most obvious.

The success of any project is in its planning and execution. Failure of the original façade on this project was the result of a whole host of problems other than the EIFS, which reflected negatively on its installation. Panelized joints failed and windows leaked, which required replacement with proper flashing. Beyond these seen conditions, however, failsafe measures were thoughtfully implemented for redundancy. Secondary weather barriers, window flashings, drainage planes and intermediate weeps were integral to the buildings salvation.

Lesson number three: Test then test again. "The mock-up did not pass on the first try," according to Bob Hede, Conroy Brothers project manager. "When you are doing something as spectacular as a 17-story building, it is always good assurance to make sure all of your details actually work."

Lesson number four: EIFS is not stucco, synthetic, softcoat, hardcoat or European. EIFS is an Exterior Insulation Finish System. Let's stop giving monikers that do not appreciate its attributes. EIFS is engineered for application over rigid insulation board. Stucco is not. However, this has not kept people from taking a Rube Goldberg-approach to specifying stucco over foam board.

Out of curiosity, I decided to do a Google search of the term "EIFS." What this yielded (in .08 seconds) was an amazing 120,000 links on the subject. Interestingly enough, in going through the first several pages, the content was entirely about residential installation. This would seem to indicate that by and large the problems associated with EIFS are residential in nature. Ah but the skeptics will say that the subject of this article pretty much shoots holes in that theory. Does it? EIFS was replaced with EIFS. Sure, the new installation has the redundancy of a secondary weather barrier and a drainage plane. But what about all of those EIFS out there without these features? There will be the occasional problem EIFS job but for the most part, they are performing as they were intended. We do not see the sharks circling around all of the malls, offices and other building stock we have put up in the last 30 years.

Fine then, can we get past this paranoia? The original EIFS was and continues to be a good product. The new EIFS with drainage is an even better improvement. But they are not a panacea. Realizing a building's limitations, we can overcome similar pitfalls, then plan and execute accordingly.