Complete Fixing a Leaking Metal Roof: Find the Source and Seal It

Fixing a leaking metal roof often comes down to one of three places: a fastener that has worked loose, a seam that has opened, or flashing that has lifted or rusted. The leak may show up far from the actual source, because water runs down the panel before it drips.

A careful search and a few targeted repairs can stop most leaks, though some problems need a professional.

Where metal roof leaks usually start

Metal roofs are made of overlapping panels held down by screws or clips. The most common leak points are the fasteners, where a screw has backed out or its sealing washer has cracked. Seams and laps between panels can open over time. Flashing around chimneys, vents and walls can rust or pull away. Water can travel along a panel and drip far from the hole, so trace the wet area back up the roof.

Quick facts: fixing a leaking metal roof

Quick facts
Common sources	Loose screws, cracked washers, open seams, and lifted flashing
Tools	Cordless drill, sealing washer screws, roof-rated sealant, wire brush, caulk gun
Best time	Dry, mild weather, with the roof surface cool and clean
Call a roofer if	The panel is damaged, the leak is large, or you cannot reach it safely

Step 1: find the source from inside

Look at the ceiling and attic on a dry day, then again during rain if it is safe. Mark the wet spots and look up at the roof decking above them for drips, stains or light showing through. The highest dry point above the wet spot is often close to the source.

Step 2: check the fasteners and washers

Walk the roof carefully and inspect the screws along the wet area. Look for screws that are loose, rusted or missing their rubber washers. A cracked washer lets water seep down the screw shank. Replace the screw with a new sealing-washer fastener of the same size, and tighten it until the washer seals without crushing it.

Step 3: inspect the seams and the flashing

Check the seams and the flashing around the leak. Look for open laps, gaps where the sealant has failed, and rust spots along the edges. Clean the area with a wire brush, then apply a roof-rated sealant along the open seam or under lifted flashing, following the product directions.

Step 4: test with water

Once the repair is sealed and dry, test the area with a hose from the bottom of the slope upward, one section at a time. Watch the ceiling below. If the leak returns, the source is still open, and you should move back up the slope to check the next fastener or seam.

Safety on a metal roof

Metal roofs are slippery when wet, and the edges can cut. Work only in dry, mild weather, wear soft-soled shoes with good grip, and use fall protection on a steep roof. Never walk on a wet or frosted metal surface, and keep a helper on the ground for anything beyond a simple screw swap.

When a repair is not enough

If panels are dented, cracked or rusted through, a patch will not last. If the leak comes from many places, or from a valley or a large flashing, the problem may be the system rather than a single spot. A roofer can recommend panel replacement or a larger repair.

Keeping the metal roof leak-free

Inspect the fasteners and seams once or twice a year, especially after storms. Clear debris from valleys and gutters so water drains freely, and touch up small areas of paint or sealant before rust can spread.

Fixing a leaking metal roof: common questions

How to find where a metal roof is leaking?

Start in the attic and mark the wet spot, then trace the path back up the roof. Check the fasteners, seams and flashing above the highest dry point. A hose test from the bottom up helps confirm the source.

Can I use a sealant to fix a leaking metal roof?

Yes, for small areas such as an open seam or a loose flashing edge, if you use a roof-rated sealant and clean the surface first. Sealant is a temporary or minor fix, and a repeated leak needs the fastener or panel replaced.

Should I replace the screws on a leaking metal roof?

Replace a screw if its washer is cracked or the screw is rusted or loose. Use a sealing-washer fastener of the same size. Do not overtighten, since a crushed washer can leak as much as a loose one.

Is fixing a leaking metal roof safe to do myself?

Simple screw and sealant repairs on a low, gentle roof can be safe in dry weather with fall protection. A steep roof, a wet surface or a large leak should be handled by a professional roofer.

Why does my metal roof leak only in heavy rain?

Heavy rain pushes more water into weak points such as loose fasteners, open seams and lifted flashing. Light rain may not reach the gap, so the leak appears only in a downpour. The repair is still at the weak point.

How long does a metal roof repair last?

A correct repair with the right fastener and sealant can last for years. A patch on a damaged panel or a rusted edge is often temporary, so plan a longer-term repair or replacement when the damage is extensive.

Can rust cause a metal roof to leak?

Yes. Rust can eat through panels, flashing and fasteners, and it can open seams. Clean the rust, treat it with a metal primer and paint, and replace any panel that is rusted through.

When should I call a roofer about a leaking metal roof?

Call a roofer if the leak is large, if you cannot find the source, if panels are damaged, or if you cannot reach the area safely. A roofer can inspect the whole system and give a written repair estimate.

Fixing a leaking metal roof: find the source first

Water on a metal roof often travels along a purlin or a seam before it drips, so the stain on the ceiling may not sit directly under the leak. Start the search from the attic during a rain shower, and mark where the light or the water appears. Fixing a leaking metal roof works best when you find the real entry point rather than the first sign of water. Fixing a leaking metal roof is easier when the panels are dry and the day is mild.

Check the fasteners

Worn washers on the screws are the most common leak source on exposed-fastener panels. Replace loose screws with sealing-washer fasteners of the same size. Do not overtighten them, because a crushed washer will leak too.

Seal the seams

When fixing a leaking metal roof seam, clean the surface first and make sure it is fully dry. Apply a roof-rated sealant according to the product label. Avoid applying it in cold or damp weather, since many sealants need dry, mild conditions to cure.

Look at the flashing

Flashing around chimneys, vents and walls is a frequent leak point. Check the caulk and the metal edges for gaps, and reseal as needed. Fixing a leaking metal roof around a chimney needs extra care, because that joint moves the most. If the flashing is bent or lifted, a simple patch may not hold, so replacement is the safer choice.

Safety on a metal roof

Before fixing a leaking metal roof yourself, weigh the risk honestly. Wet metal is slippery, and a steep roof is dangerous even in dry weather. Use fall protection, soft-soled shoes and a helper on the ground. Large or steep areas should be left to a roofer, who can also check the metal for corrosion that a simple repair will not fix.

When the leak keeps returning

If a metal roof keeps leaking in the same place after repeated fixes, the panel may be cracked or the underlayment may be failing. Keep a record of each fix, so you can describe the problem clearly to a roofer. Fixing a leaking metal roof that returns usually means the damage is larger than it looks.

Related reading

• Simple Metal Roof Installation Cost: What Drives the Price
• Practical Roof Leaking in Heavy Rain: Find It, Protect It, Fix It
• Practical Guide: How to Find Where a Roof Is Leaking
• How to Remove an Ice Dam Safely Before It Leaks

Browse all roofing guides, or find a roofer in your city from the roofing directory.