Adding piers is not always the solution to a foundation problem. Particularly a heaved foundation.
Our expansive clay soils in the Dallas and Fort Worth area wouldn’t be a problem if kept uniformly moist (not wet) all the way around the foundation. When an area of a foundation is consistently moister than the rest of the house, the foundation will heave in that area.
The best way to achieve uniform moisture and reduce or even eliminate the heave in a concrete slab may be a combination of drainage correction, adjusting watering, and by adding a strategically placed french drain.
An effective french drain is typically installed to a depth at least as deep as the bottom of the foundation beam. This depth assures the removal of sub-surface water.
A french drain will not fix a heaved foundation overnite. It may take 6 to 12 months to stabilize. But for sure, a french drain can be a smarter repair than raising the unheaved foundation to the heaved level.
If you are an investor looking to buy and flip a house with foundation problems that include a severe heave problem, you had better allocate a year for the foundation repair. First fix the water caused problems, the source of the upheaval. Then, after allowing 6 to 12 months for moisture stabilization, determine if the foundation needs underpinning.