Standing seam metal roofing systems can be divided into two basic categories: structural and architectural. Structural and architectural systems are designed, engineered and installed to satisfy different metal roofing requirements.
Architectural metal panel roof systems and structural metal panel roof systems are installed over a large variety of substrates. There are two general categories of substrates: continuous or closely spaced decking that provides solid support for the metal roof panel, and the other is composed of spaced structural supports (such as purlins) where the metal panels must span between supports. Most structural metal panels are used over spaced structural supports without being supported by a solid roof deck.
Structural Metal Roofing Panels
Structural roofing panels are designed to span across open purlins, and can carry snow and wind loads without a solid deck. However, structural panels can also be installed over a solid deck.
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Structural metal roofing panels have higher seams, typically between 1½- and 3-inches tall. Structural panels are either mechanically seamed or “snapped-together,” depending on the design. Structural metal roof panels can be installed on slopes as moderate as 1/4:12. They can also be applied on steeper slopes, and can even be applied vertically as a wall panel.
Structural metal roof systems are designed to allow unlimited thermal movement as the panels expand and contract with temperature variations. This is crucial, especially when longer panels are used. Clip design and system details make this possible.
Architectural Metal Roofing Panels
Architectural roof panel systems are intended for use on steep slope applications, generally 3:12 or greater. Architectural metal roof systems require a solid substrate to support the panels. An underlayment should also be installed to protect against moisture penetration. Image may be NSFW.
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Architectural metal panels have lower seams (½- to 1½-inches) than structural metal roof systems. Architectural panels can either be mechanically seamed or “snapped together,” depending on the panel’s design. Architectural metal roof systems are hydrokinetic (water shedding), not hydrostatic (water-tight). These systems should shed water quickly, and should not endure static water pressure.
