Corrugated roofing typically is made of a metal that is shaped so that it runs in waves. The roof has low and high places that run up and down all the way across the roof. This wave formation in the material helps insulate the building and keep it cooler; however once it develops leaks, repairing the roof requires some work.
Scrub rust areas with a wire brush to remove flaking. Dust away particles created by the brush.
Wipe down the entire area around the leak with rubbing alcohol to remove dirt and grime.
Paint on a rust stopper so that the rust is neutralised from further destruction.
Screw a new piece of corrugated roofing over the old piece. Make it the same length as the old piece so that you can attach it to the structure. Use galvanised screws and line up the corrugated pattern so that it fits tightly.
Caulk around the edges and the screws of the piece so water doesn't get underneath.
Paint over the seams of the new piece of metal with roof coating to add an extra layer of protection.
If most of a piece of roofing is damaged, consider removing it and replacing it with a new section. Remove the nails or screws that are holding in the old piece of roofing that is damaged. Attach a new piece in its place with new galvanised screws. If you do this, there is no need to clean or repair the leak area. For small repairs, snip out a piece of new roofing the size of the leak area and glue it in place over the problem area with roofing tape instead of applying a full piece. Once it is snug to the area, screw it in place and caulk around the outside of the piece to keep water from getting underneath. Caulk the screws as well.