Retrofitting Barrier Exterior Insulation and Finish System: Methodology and Performance Assessment

Abstract

Barrier-EIFS (exterior insulation and finish system) refers to EIFS with no internal drainage plane or through-wall flashings to collect and drain water that bypasses the EIFS’s surface barrier. EIFS’s surface barrier consists of a thin lamina and exposed joint sealants at transitions to elements such as windows, projecting decks, and intersecting parapets to prevent water infiltration through the surface barrier. Breaches in the surface barrier, however, can cause water leakage into the wall and building interior. In some cases reasonable reduction of leakage and preservation of the exterior walls may be accomplished by reducing barrier-EIFS’s over-reliance on sealants, and by introducing watertight through-wall flashings at leakage-prone transitions and penetrations. The authors refer to this approach—providing flashings and localized drainage immediately around transitions and penetrations of wall elements while maintaining or improving the existing barrier-EIFS system away from such details—as “hybrid repairs.” A case study of repairs on an existing high-rise barrier-EIFS-clad building shows the in-service performance of the hybrid repair methodology. The subject building had experienced water leakage at intersections of the EIFS and other building envelope elements, including windows, doors, balcony deck-to-wall transitions, and intersecting parapets. Repairs to correct water leakage focused on creating reliable concealed flashings at these details, along with more common barrier-enhancement repairs over the original EIFS, which was generally left in place. To help evaluate the hybrid repairs’ effectiveness, the authors surveyed typical exterior repairs in place for 2–1/2 to 5–1/2 years and interior finishes in the areas of the repairs. The Authors interviewed residents in some units that had experienced chronic water intrusion prior to the repairs; residents commented that they have seen no water intrusion since the repairs. The survey and interviews with residents revealed no evidence or reports of reoccurring water intrusion, supporting the general effectiveness of the hybrid repairs on the subject building.