SINK HOLES IN FLORIDA

Sinkholes are formed where the rock below the land surface is limestone or other carbonate rock whose minerals are naturally dissolved by water. They can be shallow or deep, small or large, but all are the result of the dissolving of the underlying limestone. As the rock dissolves, the ceiling of the cavern (sometimes referred to as a void or cavity) becomes thinner. When the land above the cavern becomes too heavy for the ceiling to support, a depression or even a complete collapse of the land above can occur. Water flow also enlarges the cavern.

Hydrologic conditions, including lack of rainfall, lowered water levels, or conversely, excessive rainfall in a short period of time (especially after a drought) can all contribute to sinkhole development. New construction, new roads, and any diversion of water flow are also common culprits.

Florida is the most vulnerable state for sinkhole development, especially along the northwest Gulf Coast. In fact, the majority of lakes in Florida are believed to have been caused by sinkhole activity.

There are basically two ways to address sinkhole activity for stablizing structures: Underpinning and Compaction Grouting .

Compaction grouting actually fills in the depressions or fissures in the limerock and pressurizes the soil in the surrounding areas, increasing the bearing capacity of the soil. What compaction grouting does not do, is the recovery (lifting) of the structural itself. It is not recommended to try and lift a structure using compaction grouting alone, as it is not a precise lift. In fact, compaction grouting should normally stop once any lift is noticed on the structure. In some cases compaction grouting has been thought to have actually worsened a sinkhole and caused it to subside more quickly because of the added weight.

Underpinning is much more precise at structural recovery because it can lift at multiple points on the foundation directly at the foundation simultaneously or differentially.

Thus, if a sinkhole has been determined to exist on a property, and there is no structural damage, compaction grouting is a perfect solution. If, however, structural damage has occurred and recovery is needed (lifting of the structure), compaction and underpinning are the best solution!

However, if it has been determined that the sinkhole is a relic (no longer active) underpinning alone is an acceptable solution and no compaction grouting is necessary. If the sinkhole is still active, underpinning will hold the structure (depending upon the type of sinkhole, and whether or not the cavern roof has collapsed), but the soil underneath the structure may still subside.

Florida Law requires insurance companies to provide coverage for damage caused by sinkholes. Florida Statute 627.706 defines a "sinkhole loss" as being "actual physical damage to the property covered arising out of or caused by sudden settlement or collapse of the earth supporting such property only when such settlement or collapse results from subterranean voids created by the action of water on a limestone or similar rock formation."

In other words, not all direct causes of collapses from settlement problems fall within the sinkhole coverage.Ê The word "sudden" has been interpreted by Courts not to require the damage to occur "overnight" and damage caused by phenomenon that does not fall within the legal definition of "sinkhole loss" may possibly be covered elsewhere in your policy, depending upon the specific policy you have and the exact cause of damage.

Since all property damage due to Sinkhole activity is covered by insurance, and evidence of damage or insurance claim will result in an investigation of the soils to determine if the cause was in fact a sinkhole. If it was, the damage is likely to be covered by insurance. If it was not due to a sinkhole, your insurance will not pay for the repairs to your property. Typically, an insurance company will have a soils engineer conduct tests to make this determination.

Learn how to identify the Symptoms of Foundation Failure

Learn how to read a soils report

Learn about the types of piers

Learn about alternative repair methods

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