Galvanized Metal Roof Repair

Updated February 21, 2017

The durability of galvanised metal roofing has made it a popular roofing material for homes for many years. Although durable, galvanised metal roofing can be damaged when the protective galvanised coating covering the metal is damaged. When the galvanised coating is damaged, the base metal becomes exposed to moisture and rust quickly forms. In a short time, the rust will eat through the thin base metal of your galvanised roofing material. A rust hole allows water to leak passed your galvanised metal roof and damage the structural members of your home.

Set the extension ladder against the side of your house, with the top extending three feet beyond the eave of your home's roof. To ensure that the extension ladder is set at the proper angle, set your feet at the bottom of the ladder and put both of your arms straight out in front of you. Your fingertips should barely touch the front edge of the ladder rang closest to your eye-level. Adjust the ladder if necessary.

Measure the size of the hole in the galvanised roof with the tape measure.

Cut a piece of galvanised sheet metal four inches larger than the width and length of the hole you need to patch in your galvanised metal roof with aviation snips.

Wipe the surface of the cut galvanised sheet metal with a clean rag to clean the surface of the metal.

Press butyl tape against the cleaned surface of the cut piece of galvanised sheet metal and run the butyl gasket around the perimeter of the metal patch, keeping the outside edge of the butyl tape even with the edges of the cut galvanised sheet metal. Make sure that there are no gaps in the butyl gasket, as a gap will allow water to penetrate the metal patch.

Secure a 5/26-inch hex head adaptor into the chuck of the cordless drill motor.

Clean the repair area of the galvanised roof with a clean rag and place the cut galvanised metal patch on the cleaned surface of the galvanised roof. The hole in the galvanised roof needs to be set in the middle of the metal patch.

Run a #10 self-tapping sheet metal screw one inch in from each corner of the cut piece of galvanised metal and then place an additional #10 self-tapping screw every two inches to seal the cut piece of galvanised metal to the galvanised metal roof.

Inspect the patch to ensure that no section of the patch buckled away from the surface of your galvanised metal roof. If you see a buckle in the patch, run a #10 self-tapping screw into the buckled area to complete the repair on the galvanised metal roof.


Work on a dry metal roof only, as a wet metal roof is extremely slippery.

Things You'll Need

  • Extension ladder
  • Tape measure
  • Galvanised sheet metal
  • Aviation snips
  • Clean rags
  • Butyl gasket
  • 5/16-inch hex head adaptor
  • Cordless drill
  • #10 self-tapping sheet metal screws with rubber washers
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