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How to Tar a Metal Roof

April Dowling

Appreciated for its long lifespan, metal roofing is a low-maintenance choice for homes, sheds and commercial buildings. Although metal roofing is resistant to fire, insects and mold, unsealed portions of roof panels are subject to moisture and air, which may cause the exposed regions to corrode.

Properly maintain metal roofing.

Tarring a metal roof with wet-stick fibered roof coating seals the metal with a durable and flexible moisture-proof film that protects the entire roof for years. Tar a metal roof properly to ensure even and continuous coverage of the asphalt-based coating.

  1. Sweep the entire metal roof with a push broom to loosen and eradicate dirt, leaves, twigs and other rubble. Scrub any corrosion patches vigorously with a wire brush until all scale is eradicated, then sweep the loosened corrosion and the other rubble off the roof.

  2. Spray each metal roof panel with water from a garden hose. Thoroughly rinse the roof before tarring it to ensure proper bonding. Let the roof air dry for 24 hours.

  3. Open the container of wet-stick fiber roof coating, then stir the tar with a paint stir stick. Pour the tar into a paint tray.

  4. Roll the tar onto the edges of the metal roof using a long-handled nap roller. Apply the tar to the entire perimeter of the roof, then cut tar in around chimneys, skylights and other penetrations using a paintbrush.

  5. Fill in the rest of the metal roof with the tar, using the nap roller. Apply the tar in even, back-and-forth passes across the width of the roof, starting at one end and working across the length of the roof. Use 1 gallon of tar per 100 square feet of metal roofing.

  6. Let the coated metal roof cure for two to three days.

  7. Tip

    Check the weather forecast before starting the project to ensure the weather stays dry and warm for several days.


    Wet-stick fiber roof coating is combustible; never use the tar near heat nor flame.

    Never tar metal roofs in rainy or cold weather.