Basement Wall Failure

basement1 Cracked and bowed or bulging basement walls are a relatively common problem in residential and commercial buildings.  The first sign of damage is usually the formation of horizontal cracks.  These cracks represent some amount of inward movement due to soil pressure. Although the cracks can initially be hairline size and may not appear to be alarming, they are a major structural problem that should immediately be addressed. Usually the problem is that there is insufficient steel reinforcement within the foundation wall to resist the lateral soil pressure. The backfill soil generates a tremendous lateral or horizontal pressure that can easily bend and break unreinforced masonry foundation walls. Even walls that are filled solid with concrete are no match for the large forces involved.  For example, the horizontal pressure applied to a completely below-ground 8-feet-tall basement wall by clay backfill soil will be about 1 ton for each foot of wall length, and it could be even more if the ground becomes water-saturated.

basement2Typically, a basement failure progresses from the formation of hairline horizontal mortar joint cracks to gradual widening of the cracks and inward bowing of the wall. As the inward bowing worsens, the wall may tend to shift inward at the bottom and it could straighten somewhat. Eventually, the wall will completely collapse due to inward bowing/bulging or shifting at the base.  Usually these failures occur during or after heavy rains, when the backfill soil becomes saturated and heavy.

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Typical Horizontal Hairline Crack Formation

Once horizontal cracks form, the wall should be evaluated by a professional engineer who can specify the proper repair to prevent failure. If caught in time, the repairs can be a simple application of carbon-fiber reinforcement to the interior faces, or installation of interior steel braces. Advanced damages can require excavation for removal and replacement of the affected wall.

 

 

Complete Basement Wall Failure:

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