To create a long-lasting watertight repair on a galvanized tin roof, you need to use galvanized metal and a sealant that does not break down when exposed to ultraviolet (UV) light. This eliminates caulk and silicone sealants, as both break down when exposed to heat and UV rays. When the sealant fails, water will penetrate the hole repair, allowing rust to form under the roof repair. When rust forms, it will extend the size of the hole that you have fixed in the galvanized tin roof.
Set up the ladder to allow you safe access to the section of roof that has the hole.
Unroll a 12-inch length of butyl gasket from the roll, and place the end of the butyl gasket on the sheet metal with the outer edge of the butyl tape even with the side of the galvanized metal patch.
Press the gasket onto the metal patch as you continue to work the butyl gasket around the perimeter of the patch. When you reach a corner on the metal patch, tear the backing paper of the butyl gasket to allow you to turn the corner easier.
Cut the butyl gasket with the sharp knife when you reach the point that you started placing the butyl gasket on the metal patch.
Secure the 5/16-inch hex head adapter into the chuck of the variable speed drill motor.
Climb the ladder, center the metal patch over the hole in the galvanized tin roof and lay the metal patch onto the surface of the galvanized tin roof.
Press firmly around the perimeter of the metal patch to work the gasket onto the surface of the tin roof.
Place the head of a #10 self-tapping sheet metal screw into the 5/16-inch hex head adapter you placed in the chuck of the variable speed drill motor.
Run a screw approximately 1-inch in from the corner of the metal patch. Continue running screws through the metal patch and into the galvanized tin roof, while keeping the screws roughly 2 inches apart.
Remove all material from the surface of the galvanized metal roof before you climb down the ladder.