When has an inspector become and expert at fixing roofs, electrical systems etc. We are there to report issues or deficiencies not tell the client how to fix it. When you start telling them how to fix it you are buying into paying to fix the problem. I have been inspecting for may years full time inspector since 1994 and have wired entire homes, plumbed entire homes as well as seen to supervising the rest of building. Unless you feel real frisky and have plenty of insurance i would suggest that you tell people what is wrong and not how to fix it.