Structural Fastening for Commercial Metal Roofs

Exposed fasteners can eventually cause leaks because their rubber washers dry out and the screws loosen under years of thermal cycling, opening a path for water. Standing seam avoids this by hiding its fasteners under the seam.

A fixed clip anchors the panel at one point, while a floating clip lets the panel slide as it expands and contracts, so a long run can move with temperature without stressing the seams or fasteners.

If a metal roof cannot move, the trapped expansion forces show up as buckling, oil-canning, and stress on the seams and fasteners, which is why the clips are built to let long panels slide.

Each concealed clip is set with two fasteners into the structure, which spreads the uplift load and anchors the panel more securely than a single-fastener clip.

The edges and corners are fastened more heavily because wind uplift is strongest there, so we tighten the clip spacing in those zones to hold the panels down where the wind pulls hardest.

A commercial metal roof can be fastened directly to steel purlins or bar joists when it is a structural standing seam system, because those panels are engineered to span and anchor to open framing without a deck.

A standing seam roof can meet published wind-uplift ratings such as UL 580, because the manufacturers test the clip-and-panel assembly and document the rated load for the project's submittal.

A concealed-fastener roof does use screws, but they fasten the clips under the seam rather than through the face of the panel, so there are no exposed screw heads or washers on the surface to fail.

Fastening differs in what the clips anchor to: an architectural roof's clips fasten into a solid deck, while a structural roof's clips fasten directly to the purlins or bar joists the panels span.

The proof is the manufacturer's wind-uplift test report for the specific assembly, which shows the rated load the clip-and-panel system carries and gives the design team and inspector what they need to approve it.