Foundations in the Portland area are typically poured concrete or concrete block (CMU). Though concrete foundations can potentially last for centuries, concrete is prone to cracking, especially when steel reinforcement and footings are minimal or absent. There are frequently defects noted at foundations vents as well. Significant cracking in foundations can be quite expensive to repair.
Cracks in concrete are very common and are generally not concerning without significant tapering, offsetting or bulging. Some cracks, however, are quite concerning and require the evaluation of a structural engineer or a contractor specializing in foundation repair. Substantial cracking can be the results of insufficient reinforcement, differential settlement, and/or backfill issues.
Foundation vent issues
When the exterior grade is at or near the height of the foundation vents, vent wells should be installed to prevent water and sediment from flowing into the crawlspace during substantial rains. Vent screens also need to be intact to prevent animal entry.
Foundations and footings without proper support will eventually settle and crack. There are some options to correct this issue retroactively, such as helical piers.