Question

why are island sinks difficult to vent? we dont want a vent pipe running up through the center of the kitchen it is difficult to vent double sinks double sinks lead to double trapping and ineffective vents there is no room on the counter for an air gap fitting scraps of food are likely to obstruct the vent question 16 galvanized iron or steel drain piping shall not be installed in an attic in the ground in crawlspaces inside wall cavities as stacks (vertical pipes) that serve as waste and vent stacks

Explanation:

For the first question, island sinks are difficult to vent mainly because having a vent pipe running up through the center of the kitchen is not aesthetically pleasing or practical. For the second question, galvanized iron or steel drain - piping corrodes over time when in contact with soil, so it should not be installed in the ground.

Answer:

1. we don't want a vent pipe running up through the center of the kitchen
2. in the ground