We are wanting to use a structural ridge beam to put a new roof on our house. I have been talking with an engineer who said that we need to determine how big the footer is under our slab. However, when I dug out under the slab I discovered that there is not footer - it is a floating slab. We need some way to reinforce the slab to support the weight of the upright posts and roof, but we can't just pour piers that would go below the frost line because it would move separately from the rest of the slab. Is there any other way to reinforce the slab to hold the weight of the roof?
Apparently I used incorrect terminology. What we have is a slab that appears to have no footer whatsoever. I thought that was called a "floating slab" but apparently a floating slab still has a footer. It appears that we just have a 4-6 inch slab of concrete sitting on top of hard clay. There is no footer at all visible at the perimeter of the slab. I dug down 2 feet and dug 1 foot under the edge and there is nothing there.