A home inspector.

Consider this, when it's time for a general checkup, you visit your general practitioner and they give you the Big Picture analysis of your health. If the GP finds something unusual or something that warrants further analysis, they will refer you to the appropriate specialist.

Your home inspector gives you the Big Picture analysis of the house you are purchasing. If the home inspector identifies the need for a  detailed analysis of any of the houses' systems or structure, they will recommend the appropriate professional, which may be an experienced engineer with expertise analyzing that particular system or structure.

Therefore, hiring a professional engineer to complete a home inspection may not give you the results you desire.