Photograph of a substantial settlement crack in poured concrete.Vertical cracks in building foundations
How to Diagnose & Evaluate Vertical Foundation Cracks

Vertical foundation crack diagnosis:

Foundation cracks and movement are discussed by type and location of foundation cracks, vertical foundation cracks, horizontal cracks, and diagonal foundation cracks, and shrinkage cracking.

This chapter of the "Foundation Crack Bible" discusses in detail the process of recognizing & evaluating vertical foundation cracks and foundation damage. Foundation cracks, which are signs of foundation damage, can mean very different things depending on the material from which a foundation is made, the location, size, and shape of the foundation crack, and other site observations.

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VERTICAL FOUNDATION CRACKS - Vertical Foundation Crack Patterns

Photograph of a substantial settlement crack in poured concrete. Photograph of a substantial settlement crack in poured concrete.

In the photos shown here, substantive cracks appeared and continued to increase in size in this poured concrete foundation used to support a modular home which had recently been completed. The cracks and foundation movement were probably due to a combination of: poorly prepared foundation footings, blasting on an adjacent building lot to prepare that site for new construction, and possibly omission of steel reinforcement in the poured wall.

The cracks in this building foundation wall were visible shortly after construction as vertical hairline openings (less than 1/16" wide) in the right hand foundation wall, above grade and inside in the basement. Within a year the owner reported several times that the cracks were becoming noticeably wider.

A careful inspection of the building interior suggested that the front foundation wall and portions of the right foundation wall were settling. There were no corresponding cracks in the finished surfaces of the structure, probably because this was very stiffly-framed modular construction. Notwithstanding the absence of damage upstairs, this was a problem that deserved further evaluation and repairs.

The builder may have repaired the foundation by supporting it from below using one of the methods described at FOUNDATION REPAIR METHODS.

Photograph of a substantial settlement crack in poured concrete.


This settlement crack probably occurred during initial footing settlement. Notice that it is wider at the top than the bottom of the crack.

This suggests that the footing to the left or right of the crack has moved downwards, with further downwards movement as we move further from the crack itself.

If this is new construction and the crack does not change in width the site conditions may have stabilized.

How to Diagnose the significance of types of vertical cracks in foundations

  • Vertical foundation cracks in masonry between two structures - differential settlement or thermal movement, often seen where an add-on garage is built on more shallow footings on backfill next to a full foundation.
  • Vertical, nearly straight or wandering cracks in poured concrete, generally even width, intermittent, or more often straight - shrinkage / thermal - low risk
  • Vertical cracks, straight generally even width, in a masonry block wall, in mortar joints but possibly right through concrete block - shrinkage / thermal - low to modest risk
  • Vertical foundation cracks that are straight or stepped in brick, especially near ends of wall - expansion / thermal, potentially dangerous if wall bond courses are broken, collapse risk.
  • Vertical cracks in a foundation wall, wider at bottom than top - settlement under building. These cracks may be less serious than horizontal when found in a masonry block wall. These cracks could be quite serious when found in a brick wall, especially if bond courses are broken and there is risk of collapse.
  • Vertical cracks in a foundation wall, uniform in width, one side of crack/wall higher than the other: differential settlement in footings, possibly a serious defect; this crack may have the same cause as the tapered crack above but suggests that the footing has both broken and settled straight down at one side of the crack

Multiple vertical cracks in building foundations

Vertical foundation cracks often appear in multiples multiple cracks in one or more area.

While a vertical foundation crack could be serious depending on its cause and on the type of foundation in which it appears (stone, brick, masonry block, concrete), these are often the least threat to the building. If there is significant vertical dislocation or signs of ongoing movement, further investigation is more urgent. If the cause is shrinkage (concrete, masonry block) it is probably less of a concern than if due to settlement. A vertical crack due to earth loading or frost would be unusual.


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