Flashing works in the same way as your shingles do and should overlap the first shingle below. This is so that the water can run down the outside of your roof and not drip down the inside. When flashing becomes damaged or removed you face a very real risk of your roof leaking.
Inspecting your flashing.
Most roof leaks caused by bad flashing can be identified before they occur or at the very least early in their damaging lives. If you have a roof leak you may want to consider checking the flashing yourself or employing a professional roofing contractor to look it over properly. The first step is to look for areas of the flashing that have pulled away from the roof. This will cause cracks in the roof; cracks that water can easily get through and cause damage to your home inside.
Checking your own roof flashing.
If the roofing cement has become damaged or eroded it is vital that you replace it because this will likely be the cause for your flashing coming away from your roof and eventually causing a leak in your roof. If any of the flashing itself is damaged you should also replace this; flashing is made from a number of different materials ranging from sheet metals to rubber. One of the most popular choices at present is aluminum because it is durable, malleable and affordable. If you are in any doubt as to how to apply the roofing cement and flashing yourself then you should pay someone to do this for you because poorly applied it will easily lead to roof leaks caused by bad flashing.
The types of roof flashing.
There are two types of flashing. If you have open valley flashing, the type you can clearly see when looking at the valley where roofs meet, then you can usually check for any damage very easily but if you have closed valley flashing it is virtually impossible to check the condition of it for yourself. Regardless of the type of flashing you have on your roof and whether you believe you can check it yourself or not you should consider using a professional roofing contractor to look at it, and this way you can be absolutely certain whether or not you are likely to suffer from roof leaks caused by bad flashing.