Unique Sealant Failures
It's not every day that we see both an adhesive and cohesive sealant failure at the same location:
Improper joint design, poor material mixing, incorrect sealant selection, sub-par preparation; all leading causes of premature joint failure. The example shown below is a very uncommon example of joint failure. The main failure on this joint was an adhesive failure, meaning the sealant lost adhesive to the substrate. But in one lone area, there was a cohesion failure, which is highly unlikely to occur. Generally, an adhesion failure will continue throughout an entire joint due to improper preparation and installation. In this case it looks like one specific spot was prepared correctly but the caulk was installed too thin. Regardless of the cause of failure, this building certainly needs 100% of its sealants replacement.