Building Enclosure with an Exterior Insulation and Finish System (EIFS) Cladding – Case History
On behalf of Intertek Building Science Solutions (BSS), I recently participated in a condition survey on a multi-story institutional building that was clad with a barrier type Exterior Insulation and Finish System (EIFS) approximately thirty years ago. The owner requested the survey due to ongoing issues that included moisture entry, cracks in the EIFS, and telegraphing of the EIFS insulation board. Prior repair efforts consisted of patching/recoating the EIFS did not address the cause of the issues nor resolve them. As a result, we were also tasked with providing a root cause analysis and remedial repair recommendations.
For the survey, we reviewed construction documents, past repairs, conducted an interview with on-site maintenance personnel and completed a walkthrough of the project. Key visual observations of the building exterior were as follows:
· Telegraphing and cracks though the EIFS lamina (base coat, reinforcing mesh and finish) as well as remedial coatings occurred vertically as well as horizontally. Most of these conditions were generally aligned with joints between adjacent pieces of EIFS insulation board.
· The issues were evident primarily at areas with conditioned spaces as well as elevations with the warmest external wall surface temperatures.
· Potential bulk water entry points existed at flashings and other locations but did not coincide with all of the existing conditions and issues.
Due to what appeared to be underlying issues, an exploratory opening was made through the EIFS down to the masonry substrate. Observations of the underlying conditions were as follows:
· Multiple coatings had been applied over the original EIFS Finish Coat
· Cracks, within the EIFS lamina aligned
with joints between adjacent pieces of the 3” thick EIFS insulation board
· Moisture was evident in the opening and the insulation board
· Slight gaps and/or base coat existed between adjacent pieces of insulation board
· Air flow and movement was apparent behind the EIFS indicating the existence of a negative building pressure
In terms of findings, bulk water entry through building elements such as flashings were potential contributing factors to the ongoing issues. However, the primary cause is the existence of a significant negative air pressure difference that was drawing warm, moist air into the building through thermal gaps/pathways between adjacent pieces of the thick EIFS insulation board. As a result of these pathways, condensation in the wall occurs when warm, moist air contacts cooler surfaces which eventually results in telegraphing and cracks in the lamina between adjacent pieces of the EIFS insulation board. Below is a summary of the recommendations presented to remediate the issues:
· Balance the HVAC system to alleviate the significant negative air pressure difference
· Repair or replace building elements such as scuppers, downspouts, flashings, and parapet caps that are potential sources of bulk water entry
Remove the coating system at areas of telegraphing insulation board joints,
cracks and where any remedial
elastomeric coating has blistered
Fill gaps between insulation board
joints alleviate thermal pathways
Apply and blend new coating system
into the existing
Apply a new coating over all wall
surfaces to provide uniform
appearance and color
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