Home Addition question

We have a story and a half house in Minneapolis. There is a dining room and three season porch off the back of house. We are planning to add a master bedroom above the porch and dining room. The dining room has frost footings in place. We were under the impression the porch had footings in place as well due to 4 feet of concrete under the floor. However we have discovered there are not footings but instead what I'm told is a monolithic slab or monolithic pour. From googling it appears these are two different things. What we have is 14" thick concrete that goes 4' deep and is on sand. There is a concrete floor/cap on top. I do not know if there is rebar in the concrete. Do you think we are safe to add on top of that existing slab without reinforcing with footings? The current concrete floor is not cracked and the porch has been there for 30 years. There was a shed roof on top of the porch. Hopefully this is enough information for you. Thanks!