I'm probably more sensitive to roofing problems than most homeowners because I once owned a home with a flat roof. While the ranch-style home was very nice, on a big lot and in a very nice community, these factors did not offset the headaches I had with roof leaks. Flat roofs make it very difficult to pinpoint the entry point for water and even after extensive patching, the problem often persisted. Replacing the roof was expensive and because we live in a part of the country with seasonal temperature extremes (the Midwest), the expansion and shrinking every season made the life of the flat roof considerably less than it would have been in a more even climate.
The majority of homes in this country are traditional, shingled, pitched roofs. I believe that the majority of homeowners neglect the importance of regularly inspecting the condition of their roofs. Keep in mind that your roof is your first line of defense against the elements that include excessive winds, snow, driving rain and hail just to name a few.
In areas of the country where the weather runs to temperature extremes or where the temperature is typically on the cold side, it's a good idea to take a careful look at your roof a couple of times a year. You may find shingles that have buckled or that are missing. Shingles can also become damaged as their surface begins to disintegrate. The fall and spring are probably the best times to conduct your inspection.
If you have a particularly steep roof or if you are elderly or have some physical limitations, it's a good idea to hire a competent, licensed roofing contractor to do the job for you. If possible, try to get some references.
Always clean the gutters in the fall. The more trees you have on your property, the more you will have to pay attention to keeping those gutters free from leaf clutter. Blocked gutters can result in accumulated water working its way up under the lower shingles causing both shingle damage and possible leaks inside the house.
In areas of the country that have more moderate, warmer temperatures year round, a once-a-year inspection will often be sufficient unless you have had excess rainfall.
One of my thankfully previous headlines was what is called an ice dam. What happens is that your gutters fill with ice and subsequent rain freezes on top of the ice and pushes its way under the lower shingles. Sometimes, when the ice beneeth the shingles melts you often end up with a leak inside the house. I've been there. You can do a couple of things to minimize the chances of ice dams forming including providing increased ventilation in the attic and adding better (higher rated) insulation in the attic. Even with these preventive measures, you may still end up with ice dams forming. One solution not to try is to chip or break the ice dam manually. You probably will not succeed anyway and if you do, you may end up doing more damage to the roof than if you tried the other method that I'm going to suggest.
Now, this is not a pretty solution. In fact you may get some strange comments from your neighbors if you follow this approach. You need two things. First, buy some ice melter (calcium chloride) from you local hardware store or home center. Second, convince the female (s) in your home to donate worn-out panty house to the cause. Carefully fill the panty hose with the ice melter crystals or pellets and then tie the waist tightly. When no one is looking, climb up the ladder to the ice dam (s) and position the panty hose vertically on the ice dam with the legs slightly down over the gutters. What will happen is that the ice melter inside the panty hose will melt the ice and create a valley that will allow the water to run off into the gutters. From personal experience, this does not always completely solve the problem but it will help.
One of the first (and easier) steps in inspecting for roof leaks is to haul yourself up into the attic and take a careful look at the bottom of the roof and supporting structures. Look for any spots or sections that look like they have had water damage. Follow the damage to the highest area that is damaged. You will need to determine a point of reference to some structure on top of the roof to be able to locate the leak from the rooftop. Measure the point of damage to the nearest identifiable roof structure like a vent pipe or the chimney. This will let you find the leaking entry point when you use the measurements on the rooftop.
This is the end of Part 1. Part 2 will discuss what you can do (and when you should hire someone to do it) to make the needed repairs.