It is not unusual for us to field calls from people who want to know if slab jacking is a long-term solution for sinking concrete. Unfortunately, we do not have a black and white answer. Slab jacking is a long-term solution in most cases, but not every case.
Determining the viability of slab jacking requires understanding why the concrete is sinking. This is true whether you are talking a slab, steps, or foundation. Every sinking concrete structure is sinking for a reason. Generally speaking, the soil underneath is giving way. But that could be due to any number of reasons – each of which plays into determining whether or not slab jacking is appropriate.
Why Concrete Sinks
Concrete is a very heavy material. There is nothing new there. Understandably, heavy concrete requires adequate support from the soil underneath. If that soil is compromised, it can no longer provide the required support. The concrete sinks as a result.
Underlying soil can be compromised in a number of different ways. First is erosion. If water does not pass through soil at a slow and steady rate, it can erode areas through which it flows faster. Next is poor soil compaction. Soil that is not properly compacted before laying concrete can eventually settle. Lastly, there can be voids well below the surface that suddenly give way, causing soil closer to the surface to sink.
Understanding the Root Cause
Before we can advise on foundation or slab repair, we have to understand the root cause. As such, we may ask a customer several different questions that help us figure out what we are dealing with.
How quickly did the settling occur?
The speed at which a slab or concrete foundation settles gives us a clue as to what might be causing it. Extremely slow settling is generally not cause for alarm. On the other hand, if you were to notice significant settling occurring over just a few days or weeks, there may be a more serious problem under the surface.
How old is the house?
Older homes are more likely to experience sinking concrete due to building practices at the time of construction. Therefore, it is helpful for us to know how old the house is. We have a lot of older houses in Salt Lake City that were built before developers started paying close attention to soil quality.
Do you notice standing water after it rains?
Standing water after a rainstorm tells us a lot about a piece of property. A property may not be properly graded to facilitate appropriate runoff. It could be that downspouts are depositing too much water next to a driveway or slab. There could be any number of issues. Standing water gives us more clues.
What is your soil like?
Sometimes we ask customers if they know what kind of soil they have. Why? Because certain soil mixtures are more prone to sinking than others. Asking about soil types tells us what we might be looking at under the sinking slab or foundation. Then we will know better how to address it.
Slab jacking can be a long-term solution that lasts for as long as a customer owns his/her house. A sound repair lasting 10 to 20 years is not out of the question. Depending on the cause, slab jacking might only last 7 to 10 years. In extreme cases – for which we would not recommend slab jacking – you may get only five years or less out of it. The only way to know for sure is to have a professional come take a look.