Here are three pieces of evidence you need to consider when weighing in on the verdict of whether you should convict your old roof and adjudicate that a new one needs installed.
Cracks in the Evidence
One cracked shingle or two is probably not a big issue, but a roofer still should inspect them. A number of cracked shingles is sufficient evidence to make a solid case for a new roof.
Since one cracked shingle can be a problem, a number of cracked shingles can ruin your entire roof.