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Understanding the Difference Between Standing Seam – Commercial Metal Roofs

Metal roofs in Chicago, and everywhere else, may often look similar, but there are some very important differences in the panels that are installed. This difference comes down to the way the metal roofing panels lock down to the roof and to each other, to ensure the most secure, durable, waterproof, and attractive roof possible. Whether they are custom made panels from Pac-Clad, or fabricated panels from steel sheets in a sheet metal shop, the locking technique can make all the difference. With many different systems and deviations from the basics, below are the most popular metal roofing panel installation styles.

The most widely used style of locking metal roofing panels is the Snap Lock. This style can be used very efficiently during installation and still provides some of the best durability possible. When manufactured by Pac-Clad, the style is called Snap-Clad. Snap-Clad panels feature a 1-3/4” leg height and a continuous interlock for improved structural performance and wind resistance. A concealed-fastener clip system allows for thermal expansion/contraction while providing extraordinary hold-down strength. Two clips are available: a standard clip for most mansard and fascia applications, and a high-performance clip for roofing applications and UL 90-rated assemblies. This style is designed for roofs with a pitch of 2/12 or more.

snap clad snap lock panelsThe next popular style of installing, or locking, standing seam metal roofs is the single lock, called the PAC-150 from Pac-Clad. PAC-150 roofing panels feature a 1.5” leg height which requires mechanical field seaming to 90°.

Right after the single lock metal roofing installation system, comes the double lock installation system. The Pac-Clad standing seam roof panels are the same size and shape as the single lock, but are instead bent to 180°. This doubles the weather protection and increases the durability of the installation of these metal roof panels.

Metal roof panels from Pac-Clad and our own fabricated panels have a concealed-fastener clip designed to allow for maximum design flexibility. These panels combine an attractive thin-rib profile with superior structural performance. PAC-150 panels are designed for application over a wide variety of substrates in slopes as low as 1:12 pitch. Regardless of the panels and locking styles used, all Pac-Clad metals feature the Kynar 500 coating, which protects the metal from deterioration and color fading due to weathering, pollution, heat, salt, or dirt.

As an additional option on standing seam metal roofs, many owners and architects decide to install a snow retention system. This helps prevent snow and ice from sliding down the roof and causing possible damage and injury. The most popular snow guard system is the S-5 ColorGard. With a sleek design, this system is the most effective as it covers the entire length of the standing seam panel, while also matching the color and appearance of the existing standing seam metal roofs. The S-5 snow guard system will last just as long as your standing seam roof, without adding any unnecessary penetrations to your metal roof.

S-5 ColorGard

The decision on which metal roof panel lock system and snow guard system to install is usually based on the aesthetics and design of the roof. Due to this, the architect involved will often specify which style will work best. With no architect involved, the decision comes down to the homeowner and metal roofing contractor.

SMART Roofing, Inc. is a full-service roofing contractor serving Chicago and its surrounding suburbs. Select SMART Roofing, Inc. as your Chicago Metal Roofing Contractor with plenty of experience with commercial metal roofs, residential metal roofs, and custom sheet metal work. From roof assessments and repairs to installations of virtually every type of new residential roof and commercial roof, our commitment to excellence, stellar customer service and exceptional results are the “SMART” roofing difference. Contact the roofing experts at SMART Roofing, Inc. at (847) 797-0404 to learn more, email us for your residential or commercial roofing needs.

Some article excerpts from Pac-Clad. To learn more about metal roofing panels from Pac-Clad, visit To learn more about the S-5 snow guard systems, visit

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