ASM Introduction
ASM Introduction
1 Introduction
Architectural Metal Roofing Systems that are accepted for use in the RoofStar Guarantee Program are roll formed, non-structural, hydrokinetic (water-shedding) systems that must be installed over solid roof decks. Although some metal panels may also be designed for use as structural (spanning member) systems, only their use as an architectural metal panel system (over solid deck) is accepted in the RoofStar Guarantee Program.
Metal roofing panels are roll formed in full rafter length pans that are fastened to decks with metal clips and screws. Galvanized steel and wood are the most common deck materials used with architectural metal roofing. (Refer to Section 1.3 Roof Decks in the RoofStar Guarantee Standards for ASM Roof Assemblies for decking material requirements).
2 Attachment
2.1 Panel Clips
In-seam (hidden) attachment clips may be a one-piece stationary design that provides a friction fit to the standing seam, which allows unlimited thermal movement of the panel along its length. Alternatively, attachment technology includes built in fastening strips that are formed along the panel seams during the roll forming process and two-piece floating clips that permit a greater range of thermal movement by allowing differential panel movement to take place between the two components of the clip. Only fastening clips that are specifically listed and accepted by the metal panel machine manufacturer are acceptable for use in the RoofStar Guarantee Program.
2.2 Drag Load Fasteners
By design most architectural standing seam metal panel systems are intended to float to provide freedom for thermal expansion and contraction. Proprietary attachment clip designs permit metal panels to slide back and forth on the clip as the panel expands and contracts during the thermal cycle. Therefore, metal panels must be pinned to the structure with fasteners to prevent slippage down the roof due to gravity loads or drag loads. Live snow loads can create considerable drag on panels displacing them from their intended location. The most common place to install drag load fasteners (point of fixity) is at the roof ridge, which allows fasteners to be concealed by cap flashing. (Refer to 5 Insulation and 14.2 Installation Details for standard requirements and additional information).
2.3 Wind Uplift Resistance: Steel Sheet Metal Panel Systems
See Application Guides and Notes and Wind Uplift Resistance in ASM Design for the simplified procedure for wind design of metal roof assemblies prepared for The Roofing Contractors Association of British Columbia (RCABC) by The National Research Council, Institute in Construction, (NRC / IRC Report No. B1040-3).
2.4 Curved Deck Application Requirements
Architectural metal roof panels that are installed on curved roof decks must be roll-formed to the curvature of the decks by use of a panel curving machine, specifically designed for the purpose. Alternatively, if flat roll-formed metal panels are installed on curved roof decks, a panel stress calculation must be completed by a professional engineer prior to installation of metal panels.