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Lesson Learned: Early creation of a field mock-up allows the testing of systems that must work together operationally. Field testing ensures reduced risk during construction and reduced remediation needs during occupancy.


Situation/problem:  Criterium Engineers identified a problem with the window design where the windows would not prevent wind driven rain from entering the interior wall cavities and higher energy costs would have resulted from a lack of seal continuity.  Original design did not provide a complete detail of the window seals which created a condition where sealant applications and controlled insulated air space were not continuous The selected window fabricator was to provide details during shop drawing reviews. The building has a weather barrier with a rain screen skin.  Window installations straddle the window opening and drainage plane of the rain screen.  When the primary window seal is on plane with the rain screen, it places the drainage plane behind the primary window seal.  Very little R-Value and wind driven moisture intrusion would have been the result of an uncorrected seal discontinuity.

Resolution:   An internal committee was convened once Criterium Engineers identified the problem.  The internal committee was comprised of Criterium Engineers field staff, contractor’s Quality Assurance staff, contractor’s field construction staff, window fabricator (design build), project architect and architect’s envelope consultant to analyze and develop corrective measures.  The sealant locations for the window assembly were realigned to create the primary sealant location at the weather barrier and additional silicone sealant barriers were designed to reduce risk from wind driven moisture.

Results: Re-design implemented immediately at a laboratory mock-up for field mock-up testing.  Design was successfully tested and implemented project wide.  Over 300 windows will be appropriately installed from the re-designed window installation process that provides a better control of insulation air space and better continuity of sealant joints.  By identifying the design problems before installation of the windows, significant dollars were saved through not having to re-install windows and significant energy costs were avoided for operations.