Government Study Proves Exterior Insulation Finishing Systems to be the Best Choice in Wall Cladding

A 2007 study funded by the United States Department of Energy and the EIFS Industry Members Association (EIMA), has determined that EIFS, when compared to other types of wall construction offers “superior moisture and temperature control”. The other wall constructions in the study included brick, stucco and fiber board siding. The study was conducted mainly fitting each wall type with sensors that measured and recorded temperature, humidity and moisture content among other factors.

The goals of the study, conducted at the Oak Ridge National Laboratory, were to investigate the thermal and moisture-control effectiveness of EIFS as well as their performance against other exterior claddings. Researchers also developed a computer model that depicted EIFS against numerous climatic conditions.

The research approach used in the study involved comparing the computer model simulations with actual field results, testing the thermal, air leakage and moisture control performances of several wall cladding materials over the period of one year, as well as seeing how they would stand up to harsh conditions and weather events.

General Principles

Developing design methods for engineers and architects to control air and moisture, prevent mould and increase energy efficiency was also a priority of the research study.

The EIFS features that were measured in the study included:

• Ventilated exterior claddings: claddings that is open at the top and bottom and is drained either by integrated or channeled foam systems or adhesive channels like vertical ribbons.
• Synchronous exterior and interior moisture management: Using appropriate water vapour transmission transport properties for the material in question that allow the walls to dry faster.
• Liquid applied water-resistive barrier coatings: These materials have specific humidity and moisture regulation applications to EIFS.

The study also found:

• EIFS did not collect or keep as much moisture or for as long of a time period as brick clad and cementitious fiberboard siding.
• EIFS that utilizes grooved insulation board enhances the venting capabilities of the walls.
• The four-inch expanded polystyrene insulation board of the EIFS system, without any interior stud insulation or fiberglass, provided better results than any other.
• Exterior insulation is far more efficient than other insulation methods.
• The water-resistant barrier coatings of EIFS outperformed other claddings that utilized building paper significantly.
• EIFS moisture levels were acceptably low and consistently so.
• EIFS with a liquid-applied moisture resistive coating easily dispersed moisture introduced through flaws in the overall building envelope.

Later phases of the study emphasized the growing concern and awareness of green construction, energy conservation and energy efficiency, and the choice of exterior cladding on walls directly correlates to and effects these factors. The study has shown that EIFS are more than superior to other forms of exterior wall claddings in both mixed and coastal climates, as well as maintain moisture and temperature in a matter that makes them perfectly suitable for environmentally conscious building and design.