The home owner does not have to be there. However, the buyer should be there. I like them to be there the whole time during the inspection. This way I can point out the stuff that they cannot see about the home. I take pictures on sight. At the end of the inspection, I process them so they can see places like the attic, crawl spaces, and other things like that. The inspection generally takes about two and a half hours. However, it depends greatly. I have done smaller homes of 1800 square feet and 30 year old homes that have taken four hours. The time depends on the condition of the home. If it is older or falling apart, there is a lot more to write up.