For many, a foundation inspection is the most important part of a complete home inspection. One of the biggest misconceptions people have about a foundation is that foundations are level, and if there are interior and/or exterior wall cracks then the foundation must need leveling. In my opinion as a professional inspector with 28 years of experience, no foundation is level, whether the concrete was poured yesterday or is supporting a pre-owned building. Levelness is not as important as foundation performance.
So what is foundation performance? A foundation will move over some time, as it should. Foundations are designed and constructed for movement, but that movement should not be severe enough to affect the usability of the supported structure. This means you should not feel like you are walking up or down hill; have doors or window frames that are not square or bind when closing or opening. While wall cracks could be related to foundation movement, cracks could also be structural framing related. With 2-story structures, if you feel unevenness of the upstairs floor along with door binding but do not observe the same conditions downstairs, this would be evidence of deflection or movement with the 2nd floor elevation structure, not the foundation.
So how do I inspect a foundation? I use my 28 years of experience as a professional inspector to observe foundation performance; inspect and observe visible framing, wall coverings, ceiling boards, floor coverings, doors and windows; while operating doors and windows. When necessary, I will use a Smart Level to perform a Foundation Elevation Survey (FES). Taking my time to be detailed and thorough during the inspection to render an opinion of the foundation performance, so you can make an informed decision on the property purchase.