I have mixed feelings on the necessity for foundation work unless the foundation has really shifted and the slab has cracked. Unless they are willing to dig quite deep and do a bell bottom pier I'm not sure you won't see shifting later on if extreme conditions come back such as another drought.
@Chrisinkingwood: If the entire foundations tilts a bit one way or another, I agree. However, our foundation had one side bent quite a bit. You could set a long level on the floor and see the angle of the floor. The problem with that is some of the house remains level and so do the walls. However, the outer wall where the foundation has dropped, the walls will try to stay with the foundation, causing cracks in sheet rock and we even had a couple of doors upstairs that no longer closed properly. Just think of a small degree of angle drop along one side of a house foundation, then look at the movement that causes high up in your house. Just a 1 degree foundation drop will cause the top of a 18ft wall to move almost 4 inches at the top (or try to). That's why you get sheet rock cracks and doors don't close right. When they finished leveling off the foundation, all the cracks had closed and the doors opened and closed properly again. Allied Foundation advised me not to repair the sheet rock cracks right away because sometimes the piles do sink a little after original installation and the cracks will open again.My house is sitting on a deep layer of clay, which is susceptible to future droughts causing the clay to shrink and the foundation to shift again. Putting in much deeper columns with footings might minimize the risk, but the costs would be much too high.
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