[abb]

Over at Metabunk, we dug up this detail on how the underslab drains worked. Apparently, the diameter was changed to 6" instead of the 4" detailed on the dwg. Also, the pipe was laid at an angle to facilitate flow (herringbone pattern).

Also, note the term "perf vcp." We took that to indicate this:

[Jim W N]

I was trying to understand what I thought I didn’t know about some of these drain pipes going uphill (?). Did I get that wrong?