It's just a simple fact that all roofs have a life span. What this means, is that given enough time, even the best of them will develop leaks that have to be located and patched. Even so-called "permanent" roofs have areas of vulnerability.
Where is the Leak Originating?
The first step to take after detecting water coming into your home or business, is to find the source of the leak. Now the water dripping down in your ceiling is an area indicator, but it by no means should be considered an exact location.
Water Can Travel Under a Leaky Roof
The reason for this is simple. The plywood sheeting on a roof structure comes in 4 x 8 foot sheets, and then the roofing underlayment comes in 3 foot sheets. This means that it's perfectly feasible for water to travel up to 11 feet, after it surpasses the top surface layer.
The First Two Places to Check Out
Two key areas to look for leaks, so you can do the roof repair are around heavy mechanical equipment such as roof mounted air conditioning units, and any low areas that are caused by a sag in the actual roof structure.
Even Small Cracks Can Cause Big Leaks
You see, because metal tends to expand and contract at a different rate then asphalt, cracks can develop where things like air conditioners and large ducts meet up with the roof. Look carefully because even a small crack can be the source of a big problem.
Low Areas Often Require Roof Repair
Low areas in a roof where water can pool are also quite often the source of problems. Roofs are designed to shed water, not hold it. So once water pools up, even a tiny hole can pass up to 20 gallons per day. If you have a low area, it may have to be built up and roofed over.
Check Out All the Drain Spouts
Drains, and areas around drains, because they have so much water passing over and through them, are all to often the source of leaks. Check all your drain spouts very carefully because they are metal, and prone to separation.
Think Like a Drop of Water
The bottom line: is that before you can do any roof repair, you have to be able to locate leaks, and going about it in a hit-or-miss fashion is time consuming, and can leave your roof a big mess. Take your time, "think like a drop of water", and before long you'll have the hang of it.