I am replacing the shower pan, which moves the drain 14†toward the corner (It’s a quarter-round showerpan). The main 3†copper vent pipe has a horizontal 30†long segment, which nearly crosses the shower drain’s vertical path. The nearest connected vent is the main, which attaches to the main horizontal slope (only 26†away from the new shower drain by straight line), but there is 64†(38†downstream and 26†upstream) to the vent. There is a separate roof vent for each of two lavatories. Do I need an additional vent for the shower drain? If so, can I use a Y-connection at the drain and connect it 4 feet above the drain to the main vent? I have access in the basement, where the drains are exposed, but the ceiling is plastered. I also have access above at the shower, where the floor is removed at the shower pan location. I should note that the trap for the shower drain is 2†below the main horizontal slope drain. I have pictures at www.photo.epson.com under the email address of jawx@comcast.net. Open the “Shower Drain†Album.