Plumbing Vent Definitions & Code Q&A#2

FAQs on Plumbing Vent Tees & Wyes

Identify & Fix Plumbing Vent Tees Installed "Backwards"

We had a plumbing inspection where he stated: Plumbing Venting tees - installed backwards.

He gave no indication where or how many.. or will answer calls for questions.

We are a homeowner doing our own work, so just trying to narrow it down. From this can you help identify if at least..

1. it is going to be on a vent stack

2. it is going to be associated with an inline vent installation

3. what does "backwards" mean?

upside down,

using wrong piece..?

any help would be appreciated! On 2019-03-23 by Megan -

Reply by (mod) - Upside down plumbing vent tee connections:

Megan,


RE: Upside down plumbing vent tee connections:

I cannot give an accurate guess at exactly what's wrong where from your question. Follow the vent piping, locate all joints, connections, tees, photograph them, and post photos here or ask the inspector to be more specific if some but not all connections were improper.

Our illustration shows the proper as well as an "upside down" position of a plumbing vent tee.

Note that if the tee, seen at the vertical plumbing vent riser, were upside down, water would be trapped in the horizontal piping, ultimately inviting clogs.

On 2019-03-26 by Megan

Above and below are photos of our plumbing pipes.

I really cant see anywhere that the venting piping is backwards. We have some inline vents that I know we installed wrong and need to redo.. but the other venting connections look right to me.

It is a second home-cottage.

Below is is the inline vent for the other shower.. the inline vents for the kitchen sink and bathroom double sink needs to be installed in the vanities.

Below is the kitchen

Double vanity

Shown below is the toilet vent, it is on a y from the drain.

There is a giant support beam right behind the toilet so we had to run it this way.

Reply by (mod) -

Yep. It's frustrating when a code official says "something's wrong, you must fix it" but won't tell you enough to find and fix the issue. I'd press for clarification from the building department, but a survey of your vent and drain piping can certainly identify improper tees or wyes or elboes or Tees that are placed upside down.

by Anonymous - The horizontal vent system must have a Forty-five degree take off on the vent before the toilet of the wye

@megan,
not where I'm from. The horizontal vent system must have a Forty-five degree take off on the vent before the toilet of the wye. The wye is good but it needs a 45 fitting up on a 45-degree angle

by (mod)

Thanks for the comments and help, anon.

Followup by Megan

Thanks so much for the information.

I know we have to redo the sink ones to be closer to the p-traps. Still not sure what he means about backwards though..
thanks again!

Is the drain/vent for the toilet with the y connection ok? the photo above?

Reply by (mod)

Above on this page I illustrated "Backwards" tees in the plumbing vent line. Take another look and let me know if you need more help.

Where you're having trouble getting adequate venting, see if your local inspecdtor approves using an AAV.

Details about Studor Vents® / AAVs (Air Admittance Valves) are found at AIR ADMITTANCE VALVES AAVs