The second floor of an old 3000sq.ft. barn has shifted and sunk. There is a 15" difference between the highest and lowest point of the floor. I want to poor a new concrete layer, but I'd rather it be as thin as possible. Can I put a base of gravel first to level the ground below the concrete? Are there any special consideration in comparison to a slab poured at ground level?
Thank you for all replies
Edit following comments:
The structure is made of thick stone walls (ca. 2ft) and the second floor is supported from below by stone columns connected with arches and spaced at every 10 ft.
Because of the hilly terrain, the second floor is also at ground level on one side, so vehicles can enter the second floor directly.
The floor of the second floor is 3ft deep, made of stones packed with some type of cement (not concrete) and supports 5 ton tractors going in and out.
The sinking that took place seems to be the result of earth movements. I'm waiting for an expert report on that.