1. Mechanically seamed Hydrostatic Panels – or Structural Standing Seam Metal Roof require that two standing seam panels be engaged with a mechanical seaming tool.
Structural metal standing seam panel systems offer superior wind uplift resistance and can be curved.
2. Symmetrical Mechanically Seamed – This style of SSMR is the newest, most innovative option available. It combines the weathertight benefits of the mechanical seam with the replacement options of a two-piece snap-lock panel. Unlike the typical “directional” mechanically seamed panels, the two-piece symmetrical standing seam panels can be installed using fixed clips while still allowing for thermal movement. Combining the advantages and eliminating the disadvantages involved with the various metal roof standing seam options, the two-piece mechanical seam panel is the best option for almost any roof design. It can be curved due to its symmetrical design. Lastly, this style of standing seam metal roofing has demonstrated an ability to withstand uplift pressures well in excess of the one-piece structural standing seam panel.
3. One Piece Snap-Lock – This style of metal roof panel requires two panel seams to snap together. The direct attachment of the roof panels simulates the look of a mechanically seamed panel without the additional operation of seaming. These metal roofing panels, despite their various structural capabilities, are best suited for decked applications with slopes of 3:12 and greater. Snap-lock standing seam is less likely to be used in high wind uplift areas. This is due to the fact that more clips and attachment points are required to satisfy uplift pressures. In many instances, corner pressures (the most demanding) cannot be satisfied. This has frequently proven to be the location where roof failure occurs in windstorms. As the capabilities of structural standing seam increase and building code requirements become more stringent, the demand for this style of standing seam metal roofing has deteriorated.
4. Two Piece Snap-Lock – This style of metal roof requires both a panel and a cap or batten. The cap or batten unites two panels by snapping down onto a butterfly clip. While these panels offer very little structurally and require a solid deck with a premium underlayment for installation, they are easier to install on roofs with valleys and hips- due to their ability to be installed bi-directionally. The simplicity of the panel shape lends themselves to curved roof designs. As the capabilities of symmetrical structural standing seam increase, the demand for this style of metal roofing has deteriorated.