Standing Seam Metal Roof Flashings: Where Metal Roofs Actually Leak

Roof flashing is the metal that seals every place where a roof changes direction or meets something else: valleys, walls, chimneys, skylights, penetrations such as roof pipes, and edges. It matters more than almost anything, because a standing seam roof almost never leaks through the flat panel; it leaks at these transitions when the flashing is done wrong. Get the flashing right and the roof is watertight; get it wrong and even the best panels will leak.

A metal roof needs flashing everywhere the panels stop or meet another surface, or where there are penetrations: in the valleys where two slopes join, along the eaves and rakes at the edges, at the ridge on top, around chimneys, skylights, and vents, and where the roof runs into a wall. Each of these transitions is a potential leak, so each one gets its own custom-formed metal flashing rather than a strip of caulk.

The main types of metal roof flashing are valley flashing where slopes meet, wall or step flashing where the roof meets a wall, headwall flashing at the top of a slope, chimney and skylight flashing around those openings, drip edge along the eaves, and rake and ridge flashing at the edges and peak. We form each type from the same metal as your roof so it matches and lasts as long as the panels.

We form and hem every flashing from metal on site because formed metal channels water away permanently, while caulk is a temporary seal that shrinks and cracks in a few years. Hemming means we fold the raw edge of the metal back under itself, which stiffens the flashing and creates a clean lip that sheds water instead of wicking it. It is the difference between a flashing that lasts decades and one that fails.

Where a metal roof meets a wall, we install formed metal flashing that runs up under the wall covering and down onto the roof panels, so water is carried over the panel surface and away. On a long wall we use step or continuous flashing tucked behind the siding or stucco, never a bead of caulk on top. Roof-to-wall joints are one of the most common leak points, so we form them by hand to fit exactly.

Around a chimney or skylight, we wrap the opening with custom-formed metal flashing on all four sides, including a back pan that diverts water around the high side so nothing pools behind it. Each piece is cut and hemmed to fit that specific chimney or skylight, then sealed under the panels rather than caulked on top. These openings leak on ordinary roofs, so we flash them like the critical detail they are.

A drip edge is the metal flashing along the eaves and rakes that guides runoff off the roof and into the gutter, instead of letting it curl back under the panels and rot the deck or fascia. Yes, a metal roof needs it: the drip edge protects the most exposed edge of the roof and gives it a clean, finished line. We form ours from matching metal so it blends into the roof.

Most roof leaks start at the flashing because the flat field of a standing seam panel sheds water easily, but every valley, wall, chimney, and edge interrupts that flow and forces water to change direction. Wherever water is redirected, a poorly formed or caulk-dependent flashing eventually lets it through. That is why the flashing details, not the panels, are what truly decide whether a roof stays dry for decades.

No, custom-formed flashing is standard on every roof we install, not an upcharge, because forming metal on site is simply how a standing seam roof should be built. Cheaper installers save time with pre-made pieces and caulk, which is exactly why those roofs leak sooner.

It matters because flashing is where skill shows: forming, hemming, and sealing each transition correctly takes a sheet-metal specialist, not a general roofer who bends a few pieces and reaches for the caulk. Our C-43 sheet metal specialist runs every job and oversees the installation of the flashings. The flashing is the hardest part to get right, and it is what we do best.