"S" traps O.K.?

[dkpbxman]

I've heard both Yes and No answers to this question. Which is right?
Supposedly, this type of trap sometimes is sucked dry by the vent allowing gas into the home.

Also, has anyone ever dealt with the newer "T" traps?

Thanks for any help.

Dan

[LazyPup]

The final answer to your question would ultimately rest with your local code authority. The two primary national model codes both prohibit the use of S-traps.



"No S-Traps, Bell traps, Crownvented Traps, Drum Traps, or traps with moving parts"

REF:
International Residential Code 3201.3
Uniform Plumbing Code 1004.0

Tee Traps are fundamentally a variaton of a bottle trap which has been in use for many years, however the TEE traps have not been accepted by all codes. Here again, you would need to consult your local inspector to determine if they have been approved for use in your locality.

[dkpbxman]

Does the "S" trap prohibition apply to old plumbing? I have one on my washing machine.

Dan

[LazyPup]

If you presently have an S-trap and if it met code at the time of installation you may continue to use it, however do so with the knowledge that S traps are notorious for sucking all the water out of the trap and leaving the line open allowing sewer gasses to enter the structure.

The alternative is to convert the S trap to a P-trap, which can usually be done very easy as illustrated below.

[dkpbxman]

Thanks. Great diagram. I'll change over.

Dan

[hcj]

S trap

That reply is something I would expect from a Home Depot department clerk, not a forum supposedly staffed by experts. That revision does not make an "S" trap into a "P" trap, any more than putting Ford hubcaps changes a Chevy into a Ford.

[HayZee518]

Then I'll tell you what - take your problem to Lowes or Home Depot and leave the forum alone. Who we have here are professionals with years of experience below their belts. You don't take their advice seriously - go ask a home inspector in your jurisdiction.

[SewerRatz]

Then I'll tell you what - take your problem to Lowes or Home Depot and leave the forum alone. Who we have here are professionals with years of experience below their belts. You don't take their advice seriously - go ask a home inspector in your jurisdiction.

Adding that distance does not change a s-trap to a p-trap. You have to add that distance between the trap and the down pipe plus add a proper vent. I speak as a licensed plumber of 17 years. so I do have experience below my belt, and I am willing to bet hcj does too.

[Redwood]

Then I'll tell you what - take your problem to Lowes or Home Depot and leave the forum alone. Who we have here are professionals with years of experience below their belts. You don't take their advice seriously - go ask a home inspector in your jurisdiction.

Are you Freakin Serious?
HCJ was spot on with His Assessment of Lazy Pups reply!
I'm a plumber with 35 years in the trade and I will state with no Doubt in my mind there is nothing but S-Trap in that diagram.

Now If you want to add a vent at a sani-tee where it turns down to the drain we can have a P-Trap.

Even adding an AAV (Hack Solution) is better than what is drawn above...

picture several posts below...
Weird rule to have to have 5 posts to post a pic if you ask me

[Redwood]

Here is a P-Trap!
It's all about venting!

[Redwood]

Of course an AAV is not legal in all juristictions and a through the roof vent would be a much better plumbing job.

[jnaas2]

Some areas limit a aav to 1 dfu too. Check with the local building inspector

[Redwood]

Some areas limit a aav to 1 dfu too. Check with the local building inspector

I personally wouldn't use one on a washer stand pipe even if it was allowed. I hate em... Hack plumbing at best.
A through the roof vent is the best way.

I just used that drawing I had on file to show the way a vent should come off the line without creating a s-trap.
As far as the trap to the vent using a wye instead of a sani tee would also create a s-trap...


Note the airflow back along the top of the horizontal arm and how it is lost with the use of a wye and 45 or, combo.