You are not required to be present during the home inspection, however, it is recommended that you be present for at least a portion of the home inspection so the inspector can walk through the home with you and show you things while you are there in person.  You are paying for the inspection, so get the most out of it that you can.  Meet with the inspector and ask him questions.  If the inspector tells you there is a problem with the foundation or siding, ask specifics and what course of action is recommended to resolve the problem.