Forgive the dummy here, but I need a lesson.
How many vent lines must I have from one upstairs bathroom, one in which I have a lav sink, toilet, and tub/shower, each fixture draining into a line that connects to a stack down to the basement and out?
Is it enough to run one vent line up from the stack the sink is draining into, with that stack going down under the floor and collecting the drains from the toilet and tub/shower?
Replies
I think it depends on how close they are.
You should buy a little book on basic plumbing. They are cheap enough and you will get a little more educated. More so than I could explain in this space. Basicly your drain system, simplified of course, is like a giant tube thats bent at 90o, The part thats horizontal is the sewer line, the part thats vetical is the vent line. The vent line or soil stack goes through the roof. the sewer line goes out under ground to the city sewer or septic tank. Basicly its still one line. Now pretty much everything that has a drain in your house will have a p-trap on it and if it has a p-trap on it it has to be vented. If your on a second story and you are putting in a toilet. The best case scenerio is that you are right next to the main soil stack which should be a 4" line, so that you can tap into it for the toilet to drain into and use for a vent also. Now if the other fixtures are close enough, some codes allow for a maximum distance depending on the pipe diameter to just drain into them without further venting, however it is all ways better to vent each fixture seperately by extending the waste riser up about 4' or so and re-connecting to the main stack. If this is impractical then you could run a seperate smaller diameter vent stack in a different location.
You can vent the bathroom with a single 2" pipe thru the roof. Or at least here you can. Each trap needs to be vented correctly, which usually means that each trap has its own vent riser, but usually the risers all tie together above the ceiling. The IRC makes pretty easy reading on this subject.