I have an old carriage house on my property, probably over a century old, which sits on what is now the lowest part of my property. As a result, water runs back into it along the driveway (which also has grade issues). The shed currently has a dirt floor because of all the topsoil that has washed back into it.
I want to rehab this shed to make it more usable, but I don't have the money to do what really needs to be done, which is to tear it all down, do all the dirtwork to get drainage headed out to the street and away from my structures, and build a new building. In lieu of that, I want to make the best use of the building with the minimal restoration I can get away with.
To that end, I have shoveled all the dirt out of one side of the shed to reveal the concrete underneath and assess what I can do with it.
In the photo, you can observe the depth at which the concrete blocks were revealed. I would guess (I didn't measure) that at the lowest point, there was 10-12 inches of sediment on top of the concrete. In other places, not nearly so much. Clearly, the floor is very uneven.
What I'd like to do is build additional walls on along that support beam in the middle and across the front on this side where I'm working to create a closed-in storage room that would be safer from the elements and my dog and thieves. What can I do to make a suitable floor that would allow me to build a couple of walls and make this a secured barn-like room?
My current thought is to use gravel to create a level underlayment up to the highest point of the concrete, and then use 8x16" concrete blocks on top as the actual floor. In my thinking, that would allow water to infiltrate without causing further damage, but would also provide a strong support for a floor.
Is that a terrible idea? Is there anything better I can do at a low cost?