While metal roofs often have the least amount of repair and maintenance, they do occasionally need to be repaired. In very hot or cold climates the rubber sealing washers can deteriorate over time and will need to be replace. This is an easy job to do if you have the time to simply unscrew, replace the washer and replace the screw.
Flat roofed buildings have their own unique set of problems such as holding water and even making damage hard to see from the ground. If you are considering buying a flat roofed building always have a roofing contractor come in and do an assessment on the condition of the roof before putting in an offer.