My crawl space is just a dirt floor and only the foundation wall footings are below frost line. The dirt in the middle isn't dug as deep.

Is it necessary to dig to the frost line if the building is heated? I ask because I have little floor jacks under my kitchen that I presume the renovators put in to help support the tile and granite that was installed. This is on a crawl so it gets cold below the house but it doesn't freeze or else my pipes wouldn't be very happy