How do you fix a leaking metal roof?
Short answer. Fix a leaking metal roof by finding which of the usual leak points failed: worn screw washers, open side or end laps, loose ridge cap or trim closures, cracked pipe flashings, or rust holes. Then replace the fasteners with new washered screws, reseal laps with butyl tape, refasten trim over fresh closures and sealant, install a new pipe flashing boot, or patch with matching metal.
The usual leak points
- Fasteners. On exposed fastener panels, sun and heat crack the rubber washers and expansion loosens the screws. Replace them with new screws and washers, upsizing where holes are stripped. Do not overdrive; a crushed washer leaks too.
- Lap seams. Where panels overlap side to side or end to end, sealant dries and gaps open. Clean, reseal with butyl tape and stitch with lap screws.
- Ridge cap and trim. Closures under the ridge deteriorate or shift, and wind-driven rain gets under. Refasten trim over new closures and sealant.
- Pipe penetrations. Metal roofs use flexible pipe flashing boots that seal to the panel. The rubber cracks with age; replace it, bedding the base in sealant and fastening per the instructions.
- Walls and chimneys. Counterflashing and endwall flashing need proper laps, because caulk alone fails.
- Rust holes. Patch with matching metal bedded in sealant and fastened, or replace the panel.
How to find the leak
From the attic or ceiling, trace water uphill, then look at the fasteners and laps above that spot outside. A hose test on a dry day, from low to high, confirms it. Water can run along the panel ribs before it drips, so the source may be off to one side.
When a coating makes sense
On an older exposed fastener roof with many failing screws and laps, an elastomeric coating system with fastener and seam treatment can extend its life. It does not replace repairs to rusted-through areas.
Safety
Metal is slick when wet or dusty. Wear soft-soled shoes, step where the panel maker advises, and use fall protection. See metal roofing in Georgia and common causes of roof leaks.