FLAT ROOF SERVICES
Metal Roof Seam Repair
Metal roof leaks almost always start at the fasteners, not the panels themselves — a worn rubber washer lets water in, and it travels along the seam before it shows up inside.
Why Metal Roofs Leak at the Seams
Overlapping metal panels are joined with a gasket between them, held by fasteners with a rubber washer underneath. Over time, that washer corrodes or deteriorates, and water begins leaking in at the fastener itself. It accumulates between the panels before eventually dripping through into the building — and the rust that forms compounds the problem over time.
A proper repair removes the corroded fasteners, cleans the rust out from around the seam, and reseals it with new fasteners and a sealant system designed for metal-to-metal movement — not just more caulk over the same worn-out screws.
Who Needs This, and When to Call
Most people searching for metal roof seam repair have already noticed a specific sign: a rust streak below a seam, a drip that lines up with a fastener line, or a metal roof that’s started leaking for the first time in years despite no obvious damage. That’s the classic pattern — not sudden failure, but slow corrosion finally catching up.
This applies to standing-seam metal roofs, corrugated metal roofing over porches and additions, and metal flashing caps on parapet walls — all common on Berkeley properties with a mix of roofing generations. If your roof is metal and leaking at a seam or fastener line rather than in the open field of a panel, this is almost always the right starting point.
One thing worth knowing before you call anyone: a metal roof with scattered surface rust but no active leak isn’t necessarily an emergency. Surface rust and active fastener failure are different situations, and we’ll tell you honestly which one you’re looking at rather than pushing urgency that isn’t there.
Metal Roof Seam Repair: Common Questions
How do I know if it’s a seam problem or something else?
If the leak traces back to a fastener line or panel overlap rather than a hole in the open panel, it’s almost certainly a seam or fastener issue — the most common failure point on metal roofs.
Can rusted fasteners be replaced without replacing the whole roof?
In most cases, yes. We replace the affected fasteners and reseal the seam with a system designed for metal-to-metal movement. Full replacement is only needed when corrosion is widespread, not isolated.
Is a metal roof more or less prone to leaks than shingles?
Neither is inherently worse — metal roofs concentrate their risk at seams and fasteners rather than across the surface, which is actually easier to diagnose and repair once you know what to look for.
What causes the rust in the first place?
Age, moisture exposure, and the galvanized coating on fasteners wearing through over years of weather cycling. It’s a normal, expected failure mode on older metal roofing — not a sign of a defective installation.