One good suggestion is to hire a roofing expert or contractor to come out and take a look at the roof and give you an unbiased opinion, so you can know where you stand. It is important to bear in mind that all roofing products have a set life span that will will be listed on the package. So, if you have for instance, a home that has an 18 year old composition tile roof that was roofed with 20 year composition tiles then that would be a good clue that it is nearing the end of its life span.
However; if you are dealing with a commercial building that has some repair work that is needed as the result of mechanical work being done on it then that would be a different story all together. Roofing repair work can be bid in two ways with one being “time and material” and the other being a straight set bid.
If it is a small repair job, you may want to hire a roofer by the hour to do the work but if the repair work is extensive you may be best suited to take several set bids from several roofing contractors. One thing is certain however and that is that if your roof needs to be repaired, putting it off can lead to water damage inside of the building further down the road.