How do you fix a metal roof?
Short answer. Fixing a metal roof starts with identifying the failure: on exposed-fastener panels the usual culprits are screws with worn rubber washers, loose or overdriven screws and leaking laps, while standing seam roofs more often leak at flashing, seams and penetrations. Most fixes involve replacing fasteners with larger gasketed screws, resealing laps with butyl tape or compatible sealant, patching holes with matching metal, and reseating or replacing trims.
Diagnose by roof type
- Exposed-fastener panels, with screw heads visible on the surface: rubber washers crack in the sun, screws loosen as panels expand and contract, and side and end laps open up.
- Standing seam, with concealed clips and raised seams: leaks usually come from trims, ridge and wall flashing, penetrations, or seams damaged by foot traffic.
The common fixes
- Fasteners. Back out failed screws and replace them with the next size up and new EPDM washers, driven snug without crushing the washer. Overdriven and underdriven screws both leak.
- Laps. Clean and reseal side and end laps with butyl tape or a sealant compatible with the panel finish, then refasten.
- Holes. Small holes take a sealant-backed patch; larger ones take a patch of matching metal set in sealant and fastened.
- Flashing and trims. Reseat ridge cap, sidewall and endwall trims with closures and sealant, and replace bent pieces.
- Pipe boots. Replace with flexible boots made for metal roofing, bedded in sealant and fastened with gasketed screws.
- Surface rust. Wire brush, prime with a compatible primer and paint; rust that goes through needs a patch or new panel.
Things to avoid
- Copper or lead in contact with steel panels, and graphite pencil marks on Galvalume, all of which promote corrosion.
- Walking on panels between supports, which dents them and opens seams.
- Coating the whole roof in tar.
Metal is slick when wet or dusty, so steep metal roofs are a job for a crew with fall protection. See metal roofing in Georgia and common roof leak causes.