The above ground drain portion for the basement is limited to the laundry box, utility sink, bathroom lavatory and kitchen sink. Although the Chicago Plumbing Code requires a minimum pipe size of four inches for all concealed (below grade) plumbing, a two inch pipe size suffices for the above grade drain plumbing from the various sinks.
The majority of the DWV plumbing is devoted to the venting portion, which also uses a two inch pipe size.
As with the utility room installation, this task requires spatial thinking skills. Peter and Thomas (the two installers) had to have a mental image of the finished product or final layout before they started the job. Furthermore, they had to account for the hot and cold water plumbing and how it would fit around the DWV pipes.