My question(s): what determines if foundation is substandard? How does one figure the lifespan of a post & pier and concrete block foundation (on sandy soil w/ no drainage problems)? Are there any other remedies aside from replacing the entire foundation and joist system? Our story is below... We were in the middle of selling our beach house (40 yrs old) on Pacific coast in WA. House inspector didn't see anything structurally unsound with foundation, but noted missing mortar in concrete blocks and suggested further inspection by foundation expert. Pest & Dry Rot inspector (different person) also did not observe any problems with post and beam foundation or concrete blocks. Long story short, third inspector isn't a "foundation expert" although my understanding is that he is a general contractor with some experience in foundation repair/replacement. His response was as follows: "The structure is typical in construction methods used at time of construction. I do not observe anything that would suggest immediate failure of the foundation; however the foundation is substandard and likely would not perform well in any seismic event. Further more the owner should consider replacing the foundation and joist system within the next 10 years, at the first signs of settlement and definately before any major remodeling project is undertaken." We have no indication that the joist system is failing and all 3 inspections revealed no strucural issue at this time. I am confused. How can the foundation be good and bad?