When homeowners think about damage to their roofs, what usually comes to mind are pretty obvious things that are hard to miss such as loose shingles or full-blown leaks. Unfortunately, many roofing issues are a little bit more subtle and it takes a well-trained eye to be able to spot them. In fact, to somebody without the proper training, the majority of roofing problems are virtually invisible. To help you avoid a huge roof repair bill, we give you three such examples.