New Government Study Touts the Benefits of EIFS

Atlanta-based Sto Corp., a cladding, coating, and restoration systems provider, recently announced the findings of new research on EIFS by the government testing group Oak Ridge National Laboratory (ORNL). According to Sto officials, the 2006 studies show that walls made of EIFS provide “superior moisture and temperature control” as compared to several other common types of wall construction.

Still under way, the government research initiative scientifically compares EIFS (exterior insulation and finish systems) with walls made with brick, stucco, and cement fiber board siding. The study was funded in part by the U.S. Department of Energy and the EIFS trade group EIMA, of which Sto Corp. is a member. A summary release on the study’s initial findings was issued recently by Achilles Karagiozis of the Building Envelope Group of the Oak Ridge National Laboratory.

EIFS Compare Favorably
These preliminary results decisively show that EIFS are a better cladding for buildings than the other three types studied. The conclusion was based on the side-by-side performance of the wall assemblies under conditions that can lead to moisture intrusion and temperature swings. In total, 15 configurations of wall cladding materials were incorporated into a specially constructed building in Charleston, SC, for comparison and evaluation over a period of 3 years.

In the statement released by Dr. Karagiozis, ORNL’s researchers assert that this new research is “useful ... in demonstrating the superior moisture and temperature control performance of EIFS as compared with other types of exterior claddings.” Among the conclusions, it is stated that “EIFS drainage assemblies with vertical ribbons of adhesive provide a drainage path and air space that contributes positively towards the hygrothermal performance of the walls.”

Water and Moisture Protection
Other findings compare the effectiveness of construction materials used to protect against the intrusion of water and moisture into buildings walls, which can cause rust, rot, and other structural damage. Housewraps, for example, were found to permit more moisture movement and accumulation than water-resistive barrier coatings, which are troweled, rolled, or sprayed on. In addition, “the use of polyethylene vapor retarders is not a good strategy” in temperate climate, reads the ORNL summary.

The study also provides insights as to the best ways to insulate buildings. “Insulation is more beneficial when placed toward the exterior,” says the summary. A summary of the research project was recently released by the Building Envelope Group of the ORNL. Highlights of the study follow, which were revealed in the memo titled “The Hygrothermal Performance of Exterior Wall Systems: Key Points of the Oak Ridge National Laboratory NET Facilities Research Project”:

• BACKGROUND: The 3-year testing program was initiated and funded through the U.S. Department of Energy (DOE) and in part by a non-profit trade group, the EIFS Industry Members Association (EIMA). The study was conducted independently by the Oak Ridge National Laboratory (ORNL), which is funded by the U.S. DOE.
• RESEARCH METHOD: Goals of the ORNL study were to confirm the performance of EIFS for insulating ability and moisture resistance. Field research was conducted for 15 months on a specially made test building constructed with various cladding materials and fitted with sensors to record moisture content, humidity, temperature, and other variables. EIFS walls are compared to brick, stucco, cement fiber board siding, and concrete block. The field data are being used to create a computer simulation intended to predict wall performance of the subject variables, called a hygrothermal model.
• SCIENTIFIC RESULTS: The study demonstrates that “the best-performing wall system was the EIFS wall consisting of 4 inches of expanded polystyrene insulation board without any interior stud insulation (no fiber glass),” reads the study summary issued by ORNL. “This wall outperformed all other walls in terms of moisture while maintaining superior thermal performance.”

This information was provided by Atlanta-based Sto Corp., an innovative world leader and producer of a broad range of versatile cladding and coating systems for building construction, maintenance, and restoration. To read the complete release from the Oak Ridge National Laboratory (ORNL), a government-funded program that conducts basic and applied R&D in many areas of science and technology, visit (www.eima.com/pdfs/EIMA_Executive_Summary_new.pdf).