Some cracks can be major issues and in extreme cases can cause serious problems. With the proper care, major cracks are avoidable with a good evaluation of soil, an effective engineering solution and a qualified contractor to execute properly. Something I always am looking for are signs of differential settlement. Below is a good definition
Differential settlement is the term used in structural engineering for a condition in which a building's support foundation settles in an uneven fashion, often leading to structural damage. All buildings settle somewhat in the years following construction, and this natural phenomenon generally causes no problems if the settling is uniform across the building's foundation or all of its pier supports. But when one section of the foundation settles at a faster rate than the others, it can lead to major structural damage to the building itself.
Differential settlement is not usually a sign of carpentry construction flaws, although some people view it that way. Instead, the phenomenon results when the soil beneath the structure expands, contracts, or shifts in an uneven fashion, causing the foundation to settle at an uneven rate. Thus, the villain is not the carpentry construction practice, but rather the prior evaluation and preparation of the building site itself and the construction of the foundation.
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