Concrete patios are usually made in sections. Quite often one or more of these sections will sink. In the majority of cases this is due to poor water drainage, but it can also be the result of ground movement, subsidence or poor construction.
These problems can be repaired.
First of all, any drainage or water problems need to be addressed.
Water that flows toward the affected area or tends to pool on or close to the patio, as well as water that may be coming from down spouts, will need to be channeled away from the affected area.
A good rule of thumb is for the water to be discharged approximately 15 feet away from the affected area.
There are then two options for repairing the sunken slab.
The first choice is to remove the offending slab and pour a new slab. This involves a lot of work and takes time and tends to be expensive.
If there are concrete slabs adjacent to the one being repaired there may be a color difference between the new and the old concrete for quite a while.
The second choice is to have a concrete leveling company raise the slab by concrete lifting also known as “mud jacking”.
This option is for slabs that are in good condition, slabs with numerous cracks or crumbling concrete cannot be lifted successfully.
This lifting process involves drilling one or more small holes through the slab and a special concrete mix is then pumped under pressure into the area under the sunken slab. As the new concrete is pumped in it raises the slab, returning it to its original height or position.
In some cases “mud jacking” can save as much as fifty percent off the cost of replacement.
NOTE: If the patio settles or sinks with a slope that will send water toward the house, repairs must be undertaken immediately.
This type of excessive water flow will over time undermine the foundation of the home.