The first question you should ask yourself is whether your house really have the leaks. You have to first identify the leaks before you can even think of fixing them, otherwise, what will you be fixing? The first thing you need to consider is to search for roof penetrations. Items that pierce and penetrate the roof are usually the main causes of leaks in your roof. It is almost impossible to find leaks in un-interfered shingles. This is true even on very old roofs. These penetrations are among other things, plumbing, fire chimneys, or just anything else that comes out through the roof. For those people who can access the attic, it is advisable that you climb up there, preferably with a spotlight or a strong torch. It is important to look for proof before you can finally decide what is causing the leakage. The evidence to look out for include but not limited to stains of water, marks, which are mostly likely to be black. If you cannot access the roof through the attic, it will be important that you trying climbing over the roof to go and check on the suspected areas.