Before I can start flooring the warehouse it's necessary to bring both manholes to the ground level. As the smaller manhole is set inside an area that will be paved differently from the rest of the floor, for now I'll work exclusively on the bigger one.
Laying a new ring of bricks around the hole allows me to reach the level of the stone walls. But this is not enough: I must consider the thickness of the floor (still not in place), so an additional ring will be required.
Now the thickness of the horizontal structure grows importantly, so I decide to give the hole a slightly conical shape to better distribute the weight over the vault. The new ring of bricks has a smaller diameter, and the perimeter of the lower circle is now expanded by polishing its border.
Fortunately the Das clay makes it easy, apart from the risk to get the cellar very dusty. To try avoid this, I place a cardboard sheet under the vault (closed laterally by two rubber walls) as a sort of slide, hoping this is enough to shield the basement from rubbles.
My work on the manhole follows with the filling of the square around the ring of bricks. The concrete base over wich I'll lay the floor will be then completed closing the gaps inside the stone walls.
When the cement is dry, I can place the last ring (as I said, it's a bit smaller than the others). I'll polish its surface along with the brick floor.
Another smaller circle marks the circumference of the earring I'll use as a grill for the manhole. I bought this piece long ago in a cotume jewelry store in Barcelona (Spain).
Does it look better hanging from an ear or laid over my manhole? In my opinion, there is no question.
Anyway, to build in the piece I'll need to dig a small step along the inner border of the ring, and I'll make it with my Dremel tool and a homemade sandpaper disc.
The final result still needs some finishing touch (polishing of the inner circumference - more dust!, varnishing of the bricks, etc...), but the structure is pretty much completed.
Here's the vault as seen from the basement: