Quality control guidelines for factory applied structural silicone glazing

Factory applied structural silicone application has become the preferred method of structural silicone glazing and panel attachment within the curtainwall industry. This preference is due to the fact that the factory environment can be environmentally controlled, quality control practices are easier implemented, and supervision is readily available compared to the field environment. This paper describes the proper methods for quality control learned by the authors over the past 15 years and a description of the benefits. Suggested architectural submittals regarding quality control guidelines for the surface preparation, structural silicone application, adhesion verification, and unit deglazing are discussed. Reporting this data in a logical fashion is essential so that a review by consultants, inspectors and/or building officials can be done. Guidelines for submitting this data are included. Interpretation of the data is a key part of this paper because the responsible parties must have a clear set of data to review to ensure the building owner of a successful project. Included in this paper is a unique test method utilizing a portable tensile testing device to quantify accurately the structural silicone strength to verify that the installed sealant meets the minimum requirements set forth by ASTM Standard Specification for Structural Silicone Sealants (C1184-00). This quick method of testing deglazed panels can provide accurate tensile strength of the installed silicone in 24-48 hours after deglazing without destroying the curtainwall panel assembly. Immediately after testing the installed structural silicone, the curtainwall panel can be reglazed. This unique method is beneficial because the alternative pressure testing of curtainwall units to the point where the structural silicone would reach the requirements set forth in ASTM C 1184 would substantially overload and destroy the curtainwall panel assembly. Suggested specification requirements regarding the type and frequency of quality control tests are given. When these requirements are followed, a reduction in the risk of failure with structural silicone glazed projects is obtained. Guidelines that are presented are state of the art, in concert with ASTM Standard Guide for Structural Sealant Glazing (C1401-02) and will ensure long-term performance of structural silicone glazed curtainwalls.