Does an Engineer Know more than a foundation contractor?
An engineer went to a university for 4 yrs. After graduation, the engineer worked under a registered professional engineer for 4 yrs. The engineer had to take two exams and then became a professional engineer. An engineer can explain the loads transferred. The engineer can explain how the beams are designed and how they react to the loads and the soil. The engineer can explain how rain frequency can affect a structural. An engineer can analyze beams that are affected by foundation problems such as beams from second floors or garage headers.
Most realtors recommend that a buyer or seller hire a foundation contractor because they perform "Free Inspections". First of all, there is no such thing as free inspections. The foundation contractor will make money of this inspection sooner or later. A foundation contractor thinks that walking around with a water level, laser or digital level and gets readings, that qualifies him to be an expert. Most of those contractors will come back in 3 yrs after they repair the exterior of your foundation and inform you that the interior has settled and it needs thousands of dollars to repair.
I strongly recommend that after you repair the exterior of your home, retain a structural engineer and have him inspect the property. This will ensure that the work performed was acceptable and that the foundation system was not over lifted. The engineer retained will also comment and make recommendations on the drainage which will affect your foundation system even when you have stabilized it with piers or piles.
You should also be aware, that the engineer signing off on the contractors work performed, is only signing off that the piles or piers exist under the foundation system. The engineer did not design the repair plan. He inspected the piles only.