Leaking Metal Roof Repair: Step-by-Step Instructions

Metal roofs are durable and long-lasting, but they can still leak over time. This is because metal has a high coefficient of expansion, so it moves more extensively with temperature swings.

To complicate matters further, metal roofs feature flashings and other details that also move along different directions.

How to Repair a Leaking Metal Roof: Step-by-Step Instructions

To repair a leaking metal roof, you will need the following tools and materials:

  • Butyl tape
  • Caulk gun
  • Drill
  • Extension ladder
  • Fabric shears
  • Metal-roofing base coat
  • Nail bar and hammer
  • Paintbrush
  • Putty knife
  • Roof cement
  • Screws and nails
  • Wire brush


  1. Clean the repair area thoroughly.
  2. Scuff the metal surface with a wire brush to help the sealant bond.
  3. Measure and cut a metal patch to an equal size as the hole or gap in the roof. The patch should overlap the existing metal panels by at least 5 cm.
  4. Apply a sealant to the metal surface within the pencil outline, avoiding gaps at the edge.
  5. Press the patch to the damaged area.
  6. Secure the patch with metal screws, spaced 10 cm apart, within 5 cm of the edge of the patch.
  7. Paint the patch to match the color of your roof panels.
Video: Water Pouring through our roof!! How to repair a metal roof!!

Unique Considerations

Metal roof repair patches are not as durable as the surrounding metal because they have a different expansion and contraction rate. This can cause stress, which leads to cracks, splits, and further repairs.

It is important to have metal roof repairs inspected regularly to ensure that they are holding up and that no new leaks have developed.

If you are not comfortable repairing a metal roof yourself, it is best to hire a qualified professional.

Sealants for Leak Repairs

Sealants play a vital role in repairing metal roof leaks. They are perfect for filling gaps created by mechanical fastener heads and other roof penetrations.

Over time, fasteners on metal roofs can back out due to expansion and contraction cycles, creating issues like missing or loose fastener heads.

When these leaks occur, the recommended solution is to replace the screws, install new washers and fasteners, and then apply a high-quality sealant over each fastener head.

High-solids polyether or silicone sealants are considered the best options. They adhere excellently to the metal and blend seamlessly with the roof color while forming a durable seal.

Silicone sealants in particular, perform well in high-temperature zones, especially when dealing with dark, UV-absorbing colors.

Roof Tapes: A Handy Solution

Rooftop tapes are another effective solution for fixing metal roof leaks. On lower slope metal roofs, like those on large commercial warehouses, leaks often occur along seams and gaps.

High-quality roof tape can be easily applied by one worker, and it can follow various shapes, including 180-degree turns.

Critical to the process is using tape with a polyester scrim to ensure flexibility and performing a thorough cleaning of the area before application.

After applying the tape, a roller is used to activate the adhesive, followed by a quality check to ensure there are no voids or loose spots.

Tapes for Gutter Repairs

Roof tapes are not only excellent for repairing roof leaks but also for addressing gutter issues. For gutter repairs, a thicker tape with a coating is recommended.

This eliminates the need for an additional coating after installation.

Addressing Ponding Water

Ponding water caused by heavy equipment like AC units is a common problem in large commercial roofs.

Roof tapes can effectively address these issues and can even be painted over to match the roof color.

Advanced Solutions

More advanced solutions are being adopted by contractors, such as two-part urethanes applied over the tape, or coating the entire roof to create a continuous seal that offers warranties lasting up to 20 years.

Causes of Metal Roof Leaks

If you have a metal roof, it is important to inspect it regularly for signs of leaks. If you find a leak, it is important to repair it as soon as possible to prevent further damage to your roof and home.

The most common causes of metal roof leaks include:

  • Metal roofing screws: Screws that are overdriven, underdriven, or installed at the wrong angle can all lead to leaks.
  • Stack flashings: The seals around stack flashings, which are the boots around pipes and other penetrations in the metal roof, can be damaged by expansion and contraction.
  • Missing sealants: Sealants under ridge caps, flashings, roof transitions, and pitch pans can wear over time and need to be replaced.
  • Curb flashings: The flashing and sealant around HVAC units can be difficult to install and can erode over time.
  • Seams and overlaps: Seams between overlapping metal panels can cause leaks if they are not properly sealed.

In addition to the above causes, metal roof leaks can also be caused by:

  • Rust: Rust can weaken the metal roof panel and make it more susceptible to leaks.
  • Hail damage: Hail can damage the metal roof panel and create openings where water can enter.
  • Wind damage: High winds can loosen or damage metal roof panels, which can lead to leaks.
  • Improper installation: If the metal roof is not installed properly, it is more likely to leak.

Tips for Preventing Metal Roof Leaks

  • Have your metal roof installed by a qualified professional. This is the most important step in preventing metal roof leaks. A qualified professional will know how to properly install the roof to minimize the risk of leaks.
  • Inspect your metal roof regularly for signs of damage or wear. Pay particular attention to the seams, flashings, and penetrations of the roof. These are the areas where leaks are most likely to occur.
  • Repair any damage or wear as soon as possible. If you notice any damage to your metal roof, don’t wait to repair it. The longer you wait, the more likely it is that the damage will worsen and lead to a leak.
  • Keep your metal roof clean and free of debris. Debris can build up on your metal roof and trap moisture, which can lead to rust and corrosion. Be sure to clean your roof regularly, especially after heavy storms.
  • Have your metal roof professionally maintained on a regular basis. A professional roofer can inspect your roof for any potential problems and make necessary repairs. They can also clean your roof and apply a protective coating to help prevent rust and corrosion.
  • Use high-quality materials. When choosing metal roofing materials, be sure to select high-quality products that are designed to withstand the elements.
  • Install proper flashing. Flashing is used to seal around penetrations in the roof, such as vents, pipes, and chimneys. Be sure to install proper flashing around all penetrations to prevent water from leaking into the roof.
  • Use sealants properly. Be sure to use sealants that are specifically designed for metal roofs and apply them according to the manufacturer’s instructions.
Video: How to Clean a Metal Roof: Maintenance, Tough Stains, Methods to Avoid

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