I personally do the roof inspections myself. I have hired contractors to do it in the past, however, I felt their inspection was a little rushed and the report that I was provided at the end was typically very brief and unprofessional (just my experiences). I prefer to have the Realtors and my Clients see me spend time physically on the roof and then I provide a very detailed roof report within my HI report. I personally feel that you should walk the roof (if safe). This is the best way to inspect all appurtenances, valleys, possible limb abrasions, and overall condition of shingles, tiles (chips, tears, scuffs, broken edges, fasteners in wrong places, rusted or exposed fasteners, etc. I just can’t get all this information (for the entire roof) from the ladder. Strictly speaking for myself, there is no adequate substitute for walking the roof when a safe environment exists.