Any cover on a building is open for damage since it is what protects the building from the elements. Hot sun and then the fast cooling at night means that most of the materials expand and contract very quickly. Eventually cracks will appear and this is where the water gets in for sure. However, some of us like the flat variety, instead of the gabled, and these are particularly prone to leaks. These are usually put on additions to the building, for perhaps a garage or utility room, and are not covered by the main structure.
These are constructed with an upper and lower layer but they must be sealed correctly otherwise leaks will occur very soon. Usually a plastic, rubber or asphalt coating is applied to make it completely leak proof. However, this coating will need regular inspecting, probably twice per year, to ensure that no leaks will be felt.
Although this style of covering is common just about anywhere, it is normally those who live in warmer climes that have them since there is not much rainfall there. They will not stand up well to snow either since this is far too heavy for the structure. Also, as the snow melts, it will obviously find any small hole that has been created by the weight.
Although this flat variety had a big advantage over the gabled variety, since they are easier to climb up on for instance, they still need the attention of the experts to look them over at least twice per year. This should be done before winter sets in and in the spring when there is more rain. They are also usually cheaper than the gabled variety but they do cause more problems in the long run. It is obvious then that the professional is always needed in cases like these. Good maintenance can be done by the householder, but the professional will be needed for the complicated work. Finding one then is very important and this can often be done by asking friends or relatives where they got their work done. You can give them a call to schedule a time for them to come to your house to give an estimate.
Indeed, word of mouth is good in this instance since the satisfied customer will also talk about how the experts cleaned up after themselves, and how good the work was. In the same context, anyone who did not do good work will obviously get a bad reputation and who would want to hire someone like this?