The best way to protect a metal roof on a mobile home from rust and corrosion is to waterproof the surface. Creating an airtight seal keeps rust from forming. While rust can become an issue over time on even the most well maintained metal roofs, it is possible to repair and maintain a metal roof yourself. But you do have to take safety measures and follow some basic guidelines.
Have someone else nearby whenever you are working up on the roof, as you may need help. At the least, you should have another person hold the ladder for you. Make certain, too, that the roof is strong enough to support your weight.
Check the condition of the roof at least once a year. Inspect roof seams, flashing around vents and pipes, and any rusted areas on the roof. Clean the roof routinely to protect against rust and corrosion. Dirt collects moisture, and moisture eventually leads to corrosion. Don't forget to clean under flashings and overlaps.
Prepare the roof for coating. Sweep off the roof. A push broom is the best tool to use for this purpose. You need to remove all dust, dirt, grease and other loose debris so that roof coating will adhere properly. Scrub the roof with a solution of one part chlorine bleach and three parts water to remove rust and mildew. Use of a pressure washer may be an easier way to do this. Allow the roof to dry completely.
Sand away the rust on particularly bad spots with a coarse grit sandpaper. Take the time to apply a zinc-based primer to the sanded areas before applying the roof coating.
Seal coat the metal roof to repair pinhole leaks and patch up smaller spots on the roof that have rusted through. Depending on how thick you apply the coating, the protection could last for a couple of years. The coating is thick and needs to be stirred thoroughly before being applied with a soft bristled roofing brush or paint roller. Roof coating can also be used to seal rusted flashings.
Allow about eight hours for the roof to dry before applying a second coat. Do not apply roof coating if rain is in the forecast or if the temperature is expected to drop below 60 degrees F within the next 24 hours after the coating is applied.
Cut a piece of sheet metal to repair larger spots where the roof has rusted through. Wear work gloves and be careful of sharp edges while cutting. Size the sheet metal to fit the hole. Allow for an additional 2 inches on all sides for some overlap. Set the metal patch in place with a waterproof silicone caulk. Let dry, and then cover with roof coating.