I am attempting to remodel our basement. We would like to add a sink to a new bar in the basement. There is a soil stack servicing the bathroom upstairs shower, tub and sink. I have a couple questions.

1. Can I add the sink and not have an additional vent if the drain is within 5 feet, IE direct venting. I live in MI.

2. I would like to go through the existing cleanout as access to drain the sink. Can I add an extension pipe at the cleanout, drain the sink into that and then add a new cleanout at the end of the extension?http://i1116.photobucket.com/albums/k573/brodiemsu/sinkplumbing.jpg?t=1311620122

More information needed. What size is the stack and what's draining into it from above? Let's hear back from you. Regards, Tom

The stack is 3.5" o.d. pvc draining the bathroom shower and sink from the floor above.

Hi Brodiemsu



1) You need a vent for this setup. If you don't have a vent on this sink the sink PTRAP can get siphoned of water every time a large volume of water passes the cleanout and that will allow sewer gasses into the home... a definite no-no!

You will need to vent the sink with an 1.5" vent and connect it into the vent system at a minimum of 42" off the floor in the basement (if there is a vent down there now), or at 42" off the floor of the first floor.

You could also install a mechanical vent, called an AAV (air admittance valve), but with the fixtures above the new sink you can get "negative pressures" and an AAV really isn't made for these cases, but it is definitely better than nothing, OK?


2) Code would never allow it, but if you can find a threaded bushing that fits your cleanout threads then yeah, many people get away with installing the sink drain piping like you want as long as you install a wye fitting for the new sink drain/vent and a full-size cleanout in the end of the new drain as you planned.

Installing a drain into a cleanout is frowned upon because the cleanout fitting doesn't have direction like a wye or a sanitary tee fitting does, and waste from above can kind of flow into the new drain pipe coming out of the cleanout... make sense? In most cases, it isn't usually a big deal... see image below.

Questions... let me know?

Mark

Mark said it! Follow his advice and vent your sink. Need more help? We're as close as a click. Good luck, tom