The Foundation Performance Association publishes a document that lists many different types of distress that are commonly and incorrectly attributed to foundation movement, but which are not usually caused by foundation movement. Every home inspector should read and reread this document very carefully. The title of the document is Distress Phenomena Often Mistakenly Attributed To Foundation Movement.
Examples of distress phenomena commonly misidentified as due to foundation movement
Masonry cracks along steel lintels
Steel angles are used as lintels to support brick veneer above window and door openings. As the house ages, these lintels will begin to rust. When steel rusts, it expands in volume, at least initially. As the lintel steel rusts the expanding lintel pushes the brick above the lintel upward creating a horizontal crack in the brick veneer.
In some cases, the lintel may rust enough that the lintel will need to be replaced. We rarely see this until the house is at least 50 or 60 years old.
Spalled concrete at corners of foundations supporting brick veneer walls
This results from the normal shortening of the concrete slab due to the concrete curing process or the expansion of the brick units due to the absorption of moisture by the brick, or both. The important point here is that a wedge or corner crack does not affect the overall structural performance of a slab foundation. It may or may not need to be repaired, but it is a concrete repair and not a foundation repair.
Sags and cracks in conventionally framed ceiling drywall
These are generally due to framing irregularities, over-loading or age. It would be very unusual for cracks and sags in a conventionally framed ceiling to be due to foundation bending.
Cracks in gambrel and vaulted ceilings
The cracks in these types of ceilings are not normally due to foundation movement. These cracks are normally due to the way the vaulted type frame structure transfers loads. The best solution is to repair these cracks with a product called Magic Corner.
Horizontal and vertical cracks in walls
Foundation bending causes a framed wall to rack. Racking creates diagonal stress patterns in the drywall; it does not normally create horizontal or vertical stress patterns. They are far more likely to be due to framing irregularities, poor drywall fastening and finishing that to foundation bending.
Doors that do not latch, will not open or close and ghosting doors
This is always due to a misaligned door frame, a door assembly that is not shimmed tightly to the frame, door hinges that are loose, or foundation bending. In any case, a ghosting door is easily corrected without underpinning a foundation.