Rationale for Joint Seal Continuity Evaluation
It has generally been acknowledged that there is a need for sealants installed in construction jointing to perform as intended over their expected service life. However, building owners perhaps have only recently become aware of the consequences of not ensuring adequate early performance of the joint seals following their installation. As Klosowski said back in 1989, “Sealing is a minor item when the cost of a building is considered… [Therefore] the importance of sealing and sealants is often overlooked" .
What have been the implications of Klosowski’s insight? Historically, not a lot of attention has been given to the preparation of design details and the specifications for construction joint seals. In addition, methods of inspection to ensure a complete joint seal, during or after installation, have not been common in practice. Nevertheless, the fact that sealant products are an important element for ensuring the air – and water-tightness of the building envelope is understood by many expert practitioners. For example, according to Scheffler , “Sealants are a primary defense against water penetration and air infiltration [or ex-filtration] in building facades, and their performance is critical to the overall performance of the entire building envelope."
The consequence of failed seals in building joints is likewise understood in instances in which the envelope relies on single-stage joints to ensure watertightness. Lstiburek , for example, has consistently asserted that, based on decades of research, joint-sealant-dependent wall designs are dangerously vulnerable to leakage.
Work undertaken by Lacasse et al.  helped to confirm in 2008 that substantial amounts of water—i. e., up to several liters per minute—can indeed be transported through very small inter-facial “cracks" along the bond-lines of joints of lengths ranging between 2 mm (0.08 in.) and 16 mm (0.63 in.).
Ruggiero and Myers  declared that a 1 % joint seal failure rate in buildings with a single seal can produce significant leakage problems. Significant leakage is, of course, a somewhat vague term that perhaps implies sufficient leakage to cause irritation and discomfort to the people inside the building. However, forensic investigations have determined that hidden leakage can cause serious damage to structural elements, at great cost to repair. Therefore, according to many experts, when it comes to preserving infrastructure, “unseen water [leakage] is the water to worry most about."