The foundation is the most important component effecting the stability of a structure. Consequently, any defect in the foundation should be regarded with the utmost caution and diligence in their evaluation.
The most common type of foundational defect is a foundational crack. A crack in the foundation can be evaluated based on its size, shape, location, and pattern. Length, width and continuity can all be signs of either insignificant or unstable cracks. Look at the shape and pattern and see if it occurs frequently over the wall or if it is isolated in one location. Foundation cracks occur as horizontal cracks, vertical cracks, diagonal cracks, and shrinkage cracks due to frost heave. Also, look for relationships between wall discontinuities and angles as well as wall penetrations. Any correlation between a wall crack and cracks in the floor is a sure sign of a significant problem. Cracks must also be evaluated with the age of the wall and the site conditions in mind.
Shrinkage cracks occur when the external soil is disturbed by the freezing and thawing of the seasons. Shrinkage cracks are usually either uniform in width or else wider at the top than the bottom. Cracks that continue all the way to the floor and go through the floor are usually signs of settlement issues or foundation footing problems.
In addition, when evaluating a foundation crack, it is important to determine the age of a crack. An old crack may be benign, but a newly formed crack may signify rapid changes in external soil conditions and the overall stability of the structure. Evidence of repeated repairs is indicative of an ongoing problem. Uneven wall joints or misaligned structural or frame components may also be a sign of foundational movement that has not been sufficiently compensated for.
Often, the signs of a crack are present before the crack even occurs. A foundation wall that leans or bulges is often a sure sign of trouble to come. Also, displaced bricks or masonry blocks might hide what, in a solid concrete wall would be a problem that would cause a crack. In brick walls, look for bricks to bulge at various levels. A bulging brick near the floor might be indication of soil resettlement on the outside wall, causing the wall to bulge outward, or the bricks to shift and break the mortar. In addition, in brick walls, a crack that follows the brick work from the floor the the ceiling is often a signal that there are serious structural defects. Often, brick walls are more vulnerable to damage from frost heave, water penetration, or temperature variations, since water can seep in between cracks in the mortar.
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