Problems related to pier and beam foundations can be very tough to pin-point as foundation problems since there are many things happening with pier and beam foundations that will normally not be within a standard slab on grade foundation, including the actual sagging of the beams involving the piers, or lateral movement from the piers, or uneven loading with the piers (the industry kind of foundation failure).
So not just may a pier and beam foundation be subject a similar conditions that an everyday concrete slab on grade foundation may be be subject to, but a pier and beam foundation may have additional problems that may have nothing related to the soil supporting the piers. Let's briefly talk over some of such non-soil related problems.
One of the main issues that you could have having a pier and beam foundation has about either deterioration (rotting) from the beams spanning between piers (if using wood beams) or excessive deflections (sagging with the beams). As wood beams mature, they tend to disintegrate since they're not well protected from your environment. As the years use, the beams will increasingly sag, meaning that precisely what those beams are supporting will also sag. A wall being supported by these beams will start cracking, giving the illusion that there is a foundation problem. A structural Engineer would usually manage to let you know if this is a problem
Another prevalent problem for pier and beam foundations could be the lateral movement from the piers. In many instances a floor on a pier and beam foundation is several feet out with the ground, we've even seen houses out with over 4ft away in the ground. As find out are able to imagine, if the wind pressure pushes contrary to the house these wind forces should be somehow transferred returning to the ground which means the top of those piers act as flag poles, swaying forward and backward with all the wind. It may not noticeable for the human eye, however the little movement is sufficient to develop some cracks in the walls, providing you with again the illusion that you have a foundation problem. Once again, a qualified Structural Engineer would manage to determine if this sounds like a problem.
Uneven pier loading is an additional common problem for pier and beam foundations. This is usually a problem while using design from the foundation since it pertains to knowing where to place the piers. Heavily loaded areas (like load bearing walls) and lightly loaded areas (like within the middle of the living room) could settle differentially from each other if the design had not been done right in the beginning; that is certainly, the piers for the heavy loaded may "sink" beyond the piers inside the lightly loaded areas if your piers are not properly engineered. This differential movement causes cracks inside the floors (if using brittle finishes) and also cracks inside wall. my company is a basis problem, but as well as tough to verify it since it could easily be mistaken for soil movement due to the soil moisture changing. Your best bet is to get a Structural Engineer to evaluate the challenge.
We already went through a just a few types of conditions you could face with a pier and beam foundation, in addition to being you can observe, not all problems have about the foundation. why not try these out is greater than you would think. The moral with this story is, because the truth is a crack i am not saying you do have a foundation problem, if you want an honest and unbiased opinion then have a Structural Engineer that doesn't benefit a basis repair company.