Additional piers with footings for an addition that has settling

Job ID: 36499299

Budget: $250 – $750 USD

I need specifications for structural piers to add underneath and existing addition to a home that was built in 1990 and has experienced settling.
The existing piers appear to be 10" sonotubes believed to be sitting on top and were 2 or 2 1/2' square footings. Additional piers are to be added, as per engineering specifications to IRC 2015.