Roof leaks: How can your shingles cause roof leaks?
One of the most common causes of roof leaks is loose or missing shingles. There could be a number of reasons for this. One is simply because the shingles are so old that the seal strip on the back of the shingle has just worn out and can not hold the shingle down anymore. In this case it is time to replace the whole roof. A second reason for this is because the shingles were improperly nailed. The shingles could have been nailed too high or low or the nails could be protruding through the shingle too much. Most of the time, simply properly replacing them with new ones will fix the problem unless you continue to keep losing shingles in other areas of the roof. If this happens then you may have to replace the whole roof with new shingles.