View Full Version : Bathroom Remodel - venting questions

The old college try
01-31-2007, 04:17 PM
I have an existing full bathroom that I'm remodeling. Currently the fixture drains tie in near the top end of the 4" horizontal building drain with the WC at the top, then the sink, and finally the tub. A 4" vertical vent exists at the top end of the horizontal drain placing the tub drain about 5-6 feet from the vent. The fixtures are not currently revented into the vertical stack. I plan on rearranging the fixtures and as such, the sink will tie in near the top of the horizontal drain, then the tub and then the WC will tie in about 6 feet from the vertical vent. Can all of the drains tie into the horizontal drain without additional venting, or do they require vents that tie back into the vertical vent upstream? If they require additional venting, will AAV(s) suffice?

01-31-2007, 04:33 PM
Is this in a basement, slab on grade or on an upper level?

Do any other fixtures discharge into the 4" vertical stack?

A sketch, no matter how crude, can do wonders for us.

The old college try
01-31-2007, 06:49 PM
Hope this clarifies things a bit. After looking at it again it appears that the WC currently ties in directly below the lav drain. The pipe you see a little further downstream is from the tub... which is about where the new WC and tub will tie in. The bathroom is located on the first floor (picture is taken in basement) and nothing else ties into the vent from above.

01-31-2007, 07:02 PM
The picture does nothing to show us exactly how you plan to install the new piping. We can visualize ways that it could be done properly, and also a lot of ways that it would not be done correctly.

01-31-2007, 07:05 PM
be state exact.

Oregon has one fixture, one vent per trap arm rule.

Arkansa can have up to 6 p-traps on one trap-arm if sized right.

so it may depend on which state you are in as far as how legal it is. but it don't look right to me at a glance.

good luck


The old college try
01-31-2007, 07:56 PM
Thanks for the responses to my question so far! Here is a crude sketch of what I'm hoping to do. I'm in Michigan if that helps at all. I read in the code that with a 2" drain you can be a maximum of 8 feet from a vent and 6 feet from a wet vent (excuse my ignorance, but I'm not sure of the definition of a wet vent). In this configuration will the 4" vertical vent work as a vent for the tub, WC and lav? If not, would adding an AAV to one or more of the fixtures work? I know that the code does allow them, I'm just not sure how I would configure them or if they would even work in this instance if needed. Otherwise, running vents from the WC and tub back into the 4" vertical vent would involve either somehow running the pipes through the outside wall (parallel to the existing 4" drain), or up through the ceiling joists. I'd prefer not to do this because the existing 4" vent is cast iron and I'd probably have to demo the wall in the adjacent wall to cut it and tie in.1814

The old college try
02-01-2007, 06:35 PM
Does the above sketch make sense at all?

02-02-2007, 09:01 PM
It might but my poor eyesight doesn't help matters any. Have you tried drawing it with MS paint?

02-03-2007, 05:14 AM
Hope this clarifies things a bit. 1812

A couple things I see that alarm me...
A gem cap on the end of the pipe - replace that with a 4" FIP fitting and plastic cap...
On the last 3" branch coming off the main it appears you have a fernco rubber fitting connecting the reducer to the elbow...
Replace that with a banded coupling or solvent welded PVC...

The old college try
02-21-2007, 06:41 PM
So, I replaced the cap on the end, however, when I went to replace the rubber fitting I found that the cast iron elbow under the rubber fitting is sort of rusted and does not have a clean cut but is rather broken and jagged. I attempted to place a neoprene no hub fitting in place of the existing one, but it doesn't really seem to provide a good seal because of the jagged end on the cast iron elbow. Since this joint does not carry anything other than air, will it be problem to leave it, or is there something else I can do to make it better?