Reasons for a Collapsed Concrete Porch

Major Reason

• The major reason that a concrete porch collapses is a failure of the steel reinforcing bars, or rebars, that run through the concrete. Steel rebar is susceptible to rust, especially if the concrete has cracks that permit water to come into contact with the rebar. Over time this will weaken the metal until it can no longer support the heavy concrete and it snaps, allowing the porch to collapse.

Other Reasons

• While rebar failure is a common cause for collapsed concrete porches, other events can also cause the same result. If heavy rain and erosion wash away soil beneath the porch, its foundation may become unstable. Sinkholes create space that can make a collapse more damaging by allowing people who use the porch to fall great distances and for concrete to also fall. Poorly mixed concrete, improper rebar placement and incorrect weight and load calculations can also result in a porch design that is highly likely to collapse.

Disasters

• Concrete porches can collapse during natural disasters and household emergencies. Just as earthquakes can damage a home's foundation, they can also create rifts in porches that cause them to collapse during the earthquake or at some time afterward. Floods can erode the space beneath a porch, speeding up the natural process of erosion that can lead to a collapse. Large pieces of falling debris from a home fire, hurricane or tornado can also damage a porch by putting more weight on it than its structure can bear.

Outcome

• Concrete porches are composed of many inches of heavy, dense concrete. As soon as they begin to collapse, falling chunks of material put excess weight on other portions of the porch, causing what might start out as a small collapse to multiply in size and scope. Injuries and even deaths are not uncommon with failures of residential porches that receive frequent use. Damage to buildings might fall under homeowners' insurance policies, but the source of the collapse can vary and each insurance company has its own means of defining collapses.