Under the outer walls that support the roof and/or additional stories there will be a sizeable footing that should go below the frost line. But inside the footing where the foundation is just supporting the first floor you only need a few inches of concrete.
I hope the foundation of your house is deeper than that.
Under the outer walls that support the roof and/or additional stories there will be a sizeable footing that should go below the frost line. But inside the footing where the foundation is just supporting the first floor you only need a few inches of concrete.