You need an inspector / consutant. When you hire an inspector / consultant, you are hiring an experienced professional who has training and experience in the building industry. It is the job of the inspector / consultant to not only evaluate the condition of the facility or site major systems and structural integrity, but also to evaluate how these systems are working together and identify areas that need to be watched, repaired or replaced.
Your inspector gives you the Big Picture analysis of the site you are evaluating. If the inspector identifies the need for a costly, detailed analysis of any of the site' systems or structures, the inspector will recommend the appropriate professional, which may be an experienced engineer with expertise analyzing that particular system or structure. The need for this kind of expensive, detailed analysis is rare.
Hiring a Professional Engineer on your own can be a disappointing experience. The term Professional Engineer does not mean that the individual has training or experience conducting home inspections. Additionally, a home inspection does not involve engineering analysis. Therefore, hiring a Professional Engineer to complete a building inspection undoubtedly costs more, but it may not give you the results you desire and deserve.