PVC upgrade to code - Plumbing Forum

michaelcpa · 11-27-2011, 12:13 AM

I am in the process of a master bath remodel. I need some advice on how to complete an upgrade of my 1.5 inch shower trap to a 2 inch run. I have worked with and glued PVC before. You can see in the included picture, I have a 1.5 inch shower line (immediately reduced from 2 against code) running to the wye on the 2 inch main. Patching in the new 2 inch line and 2 inch trap back should be straight forward. But my issue arises in that the wye you see to the left of the shower drain wye, which is connected to the vent stack. The connection between the wye’s is with a very short section of 2 inch pipe. This space is too small for a slip coupler. Seeing as how the new shower 2x2x2 wye will be pushed in right to glue and the 2x2x1.5 vent wye is not movable, does anyone have any suggestions on what steps to take to accomplish the connection?

**phishfood** · 11-27-2011, 01:35 AM

Move the wye for the shower trap further to the right, and use a short piece of pipe to a regular 1/8th bend instead of the street 1/8th bend into the wye that exists now. Then you should have room for the slip coupling.

**phishfood** · 11-27-2011, 01:43 AM

Something was bugging me about that picture, caught what it was when I looked again. If there is nothing draining into that 1 1/2" vent, then it is against any code that I have heard of. A dry vent cannot be run horizontal until it is at least 6" above the rim of the fixture that it serves.

michaelcpa · 11-27-2011, 02:20 AM

phishfood,

Thanks for the quick response. As far as the vent pipe goes, the 1.5 inch pile in line and upstream from the left wye is the drain for the tub, only the branch of the left wye goes to the vent stack. I attached another picture from a lower angle to my post; is this still what you consider against code as you describe in your second post?

**phishfood** · 11-27-2011, 02:28 AM

Can you see the rest of the vertical section of that vent? If there is not a small fixture, usually a lavatory, draining into it, then it is against code. The vent runs horizontal from the wye to the 1/4 bend, and unless there is water draining through that section, it is a flat dry vent.

michaelcpa · 11-27-2011, 02:48 AM

This is a second floor bath on a two story house. That vent goes vertical (later connecting to the right pipe you see in the second picture) up to the attic and definitely there is no fixture that drains into it before it goes flat into the main 2 inch line post 1/4 bend. Any suggestions on a fix. There is not 6 inchs above the main 2 inch line for any elbows. I guess it may be time to bring in the pro's for a fix! Thanks for the help!

**EricS** · 11-27-2011, 05:34 AM

Biggest problem that I see is that you did not have a vent on your existing shower trap arm. Yes code specifies that the shower trap/arm should be 2", though most shower heads are rated at 2.5 gpm while some of the new ones go even lower. A 1 1/2 drain line is rated for 1 FU horizontally which is the equivalent to 7.5 gpm. Anyway move your wye for the shower a little farther to the right with the branch rolled flat and glue the new ST 45 so that it runs parallel to the 2" drain line, next glue in a 2x2x1 1/2 wye with the 1 1/2 vent rolled up above the center line of the shower drain, run this new vent up into the wall with the other two 1 1/2 vents and tie in to tub vent minimum 6" above rim of tub. Install 2" LT 90 to go through joist to 2" p-trap. Yes you should get your vent vertically as soon as possible but running it horizontally is no problem as long as you are using drainage fittings.

**phishfood** · 11-27-2011, 12:46 PM

Different codes between Washington State and here in Florida. The latest edition of the International Plumbing Code, which is the model code for Florida, requires an 1 1/2" drain for a shower, though previous editions did require 2". The only time that an 1 1/2" drain might be a problem is if you install multiple showerheads.

And IPC specifically does not allow a dry flat vent less than 6" above the rim of the fixture. I had a bit of a time with a totally unnecessary stack vent that I needed to offset in a truss system in the floor below earlier this year. The inspector finally let me go with it when he understood that the bathroom group above had another vent serving it.

Interesting, the discrepancies between the various codes. I can see different weather conditions changing some aspects of the code, but on this particular point, I don't see vent piping being any different in Washington, Indiana, or Florida.