NRCA analyzes and tests metal

Contractor-fabricated architectural metal panel roof systems have been used successfully in the United States for years. However, there recently has been increased scrutiny about some of these roof assemblies' wind uplift-resistance capabilities.

Building code requirements mandate minimum uplift resistances for roof assemblies, and model building codes list approved test methods that determine uplift resistances for roof assemblies that cannot have uplift resistances determined analytically. Underwriters Laboratories (UL) Inc. test method UL 580, "Tests for Wind Uplift Resistance of Roof Assemblies," currently is the most common method referenced in building codes as an approved test method to determine uplift resistance of roof assemblies.

For most roofing products used in the United States, roofing contractors rely on product manufacturers to perform testing and provide the necessary documentation for building code compliance. However, because there are no product manufacturers for contractor-fabricated architectural metal panel roof systems, the responsibility for providing code compliance information typically resides with the contractor who fabricates and installs the metal panels. Steel and aluminum have analytical design methodologies that are industry-accepted; there is no industry-accepted analytical design methodology for copper. Therefore, the uplift resistances of copper panel roof systems must be determined through physical testing.

Because of this, in 1997, NRCA embarked on a testing program for contractor-fabricated copper panel roof systems. All metal panels in this study are flat-pan with double-lock standing seams. NRCA retained and analyses were performed by ENCON® Consultants Inc., Tulsa, Okla., at the Hurricane Testing Laboratory in West Palm Beach, Fla. As part of our study, theoretical analyses of contractor-fabricated aluminum, Galvalume,™ galvanized steel, terne-coated stainless steel and terne-coated carbon steel roof panels were performed to determine uplift resistances according to standard design practice.