You will rarely, if ever see a tin roof. If and when you do, you'll realize the roof may have been on that building for well over a hundred years. If it is still in fairly good condition, if the roof is your responsibility, you'll want to treat it to function properly. That won't be an easy job, and unless you're prepared to finish what you start, you should probably call an expert.
When they installed the tin roof, technology of today was lacking and they didn't seal them properly. If that is the case with the one you're looking at, the tin roof is probably in very bad condition. If you're doubtful about walking on the roof, consider replacing it. However if the tin roof is repairable, then you should take a few steps as you tackle the job.
The first thing you'll want to do is remove any debris. This includes everything from moss, rust, roof cement, old paint and possibly tar. Scrape that stuff off carefully and usually by hand. You can find chemicals to help remove the rust. After the roof is relatively clean by scrubbing, then rinse or power wash to prepare for paint.
After you've started cleaning and you realize that rust still remains, you need to take more steps to clean it. Once you're satisfied that the rust is history, apply a rust resistant primer. After the primer dries, apply an acrylic base paint. Strips of meshing is then embedded into the acrylic base, then smooth the wrinkles out. After that dries, apply a coat of acrylic primer followed by a minimum of two acrylic topcoats.
Some have attempted to patch the holes in metal roofs by soldering pieces of metal over them. However the success of this process varies greatly. If you're adamant about keeping the tin, or metal, roof, it may be easier to replace it.
A Metal roof will cost more as opposed to a more conventional roof, and the technology has improved over the years. The properly installed metal roof will last longer, have more durability and the problems of the past no longer overwhelm the home or business owner.
Those past problems of leaking and noise are gone as well. However the solid tin roof has had its own history, and no longer will be seen in this modern world, probably due to cost and availability. When you find a person that renovates the historic past and when they want the tin roof restored to its original beauty, they probably won't settle for anything other than the historic tin roof.