Any idea?

[Pillike]

I recently had underpins installed under my foundation to stabilize it from moving. The foundation under my original structure is only 30" to the bottom of the footer. Frostline in my area is 36"... common practice is to go down to 42-48" with footings. The contractor that install the underpins thought the house was sinking due to the addition of a second story on the house, myself thought it was heiving from the frost. I remodeled and added a 12' addtion out the front of the orginal building (24'x26') and added a second story loft over the old foundation. Shouldn't the newly installed underpins have gone done below the 42" mark or further?