|Posted by CEA on July 30, 2004 at 10:54:19:|
|In response to Re: shower only drain|
: do I install a vent by putting a T on top of the trap?
You need a 2" P-trap directly below the drain. From the outlet of the trap you have to run horizontally (1/4" per foot downward slope) to the vent connection. Maximum (critical) distance from the trap outlet to vent varies by local code but you will have at least 4' to work with for a 2" trap arm. The purpose of critical distance is to make sure the trap weir (bottom of pipe at trap outlet) isn't below the top of the pipe at the connection. Most codes require the vent take-off from the drain to be within 45 of vertical. Usually the trap arm dumps into the side inlet of a sanitary tee, with vent going up and drain going down--although you can also tie in the vent with a sanitary tee on its back and continue the drain horizontally. After the vent you can basically do whatever you want with the drain as long as you maintain at least 1/4" per foot downward slope. Some codes allow horizontal vents and other nonsense--if you have any doubts check with your local inspector or a professional. Good luck.