b'ARCHITECTURAL SHEET METALPROPER DESIGN DETAILS FOR STANDING SEAM METAL ROOFSBy: John A. DAnnunzioThemostcriticalcomponentofaduring heavy precipitation events.standing seam metal roof systemotherThe designer must also take into account the geographic than metal panel seamsis at verticalclimate and surrounding area of the building to determine transitions and penetrations. Industrygutter design accessories. For instance, in colder climates analysis has indicated that leaks inthe application of heated gutter strips and snow guards metal roof systems predominantly occurcan eliminate the ice build-up that poses a threat to back at metal panel joints and terminations. When specifyingup under the panels. The application of gutter guards in standing seam metal roof systems, the designer shouldheavily wooded areas further reduces the threat of water be cognizant of details at terminations, penetrations,back up from the clogging of gutters with vegetation and flashings. The elimination of moisture entry canand debris.be achieved through the proper design of flashings atThe most common design technique at these points is all vertical transitions and penetrations. This overviewthe insertion of a trapezoidal closure between the gutter provides proper design requirements at the most commonand the panels. These are typically fabricated from flashing points. Flashing design should be in compliancefoam or plastic and should be installed in accordance with the metal system manufacturers latest printedwith the metal system manufacturers latest printed specifications. specifications. The most important design element is Exterior Gutters specifying an adequate seal through adhesion. This The most important design issue at exterior gutters iseliminates the potential of wind blow-off or moisture the deflection of water backing up under the panels. Thisinfusion at unadhered openings.can occur from clogged gutters ormore commonly Gables or Rakesfrom the application of undersized gutters. Gutter widthThe critical issue regarding gable or rake trims is that should be determined by a calculation that considersthey are designed to move with the free-flowing metal the average rainfall rate in the geographic area and thepanels. This is typically accomplished by specifying the size and slope of the roof area. Larger gutter widths willproper cleats to the wall panels that will allow for the trim accommodate more flow and are less likely to back up 10 www.mrca.orgMidwest Roofer'