Incomprehensible foundation, lift shed

[micke4711]

Hello! My townhouse from 1975 has a simple cold storage. The panel is worn out, so I'm replacing parts of it, and after demolition, the "foundation" looks like in the pictures: Sturdy beams form a frame that lies directly on sand?! Asphalt cast in the frame.

One of the corners has sunk significantly, up to 10 cm. What on earth is holding up the house? It can't just be standing on the sand, can it? Is it the asphalt somehow?

I'm considering lifting the corner with a jack, digging down a concrete block under the frame, and throwing on some sill seal.

What do you think, could it work?

 

[micke4711]

I didn't get a reply, but I went ahead anyway! Not exactly "frost-free depth" but significantly better than before, I thought. I managed to lift the house to almost level, and then straighten it with diagonal tension straps and then nail straps.

The only problem now is that the door can't be closed