We are having problems with odor in our shower. I plan to replace the existing shower with a new tile shower but need to figure out whether or not the shower has a p-trap as we have been told houses on slab do not have a trap for the shower. How do we confirm if we have a trap or not? Given the odor, I'm ready to start jack-hammering...
Charlotte, nc

speedball1

We always install a "P" trap when we rough in for a shower. How you can tell if you're trapped is to remove the strainer and shine a light down the raiser. You should see standing water that's about at least 2" deep. regards, Tom

nmwirez

if there is a p-trap directly under the drain you should see water, usually a p-trap is not any farther than the shower stall perimeter near a vent stack. In a slab, the p-trap would be in the drain center as mentioned. If this is cast iron probably not to UPC code now. Try not to destroy the drain line to the center where the pan drain is because you can use a rubber sleeve over the pipe to connect new plastic DWV pipe and p-trap assembly without needing to do too much jack hammering that depends on where the vent is also. good luck. nm

doug238

try not using the shower a few days and feed something flexible down it about 10 feet. if you hit a spot where it will not go within 5 feet of the shower it may have an offset p trap. when ya pull it up, is it wet?

speedball1

"it may have an offset p trap."
Doug, Are you referring to a running trap,(see image)? Because that's what you'd have if you moved a "P" away from under the drain. In all the hundreds of "under slab" shower installations my company has installed we have never iroughed in a a running trap for a shower. Nor could i ever concieve of a situation where we would be forced to rough in a running trap in place of a regular "P" trap. Now I admit my code book is a little old and not up to date so if I'm missing something let me know. Regards, Tom

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nmwirez

Hi speedball,

Thanks for the running trap defiinition. I am learning every time you post something. I have seen a running trap in SF years ago done in metal. I guess it is still allowed nowadays? nm

speedball1

As a rule running traps are installed outside the house in a septic system if there's a odor problem. regards, Tom

Ken 297

I have seen showers without a trap and the odour is noticable.
Always done by someone that doesn't know anything about plumbing.
If you are on a City sewer system you can have someone hit the manhole cover on the street with a sledge hammer. The trap not only stops odours and gases it muffles the noise. If you dont have a trap you will hear it clear as a bell.

nmwirez

Ken, Thats clever. Will it work on a septic tank?.. nm

Ken 297

Its hard to bang on a septic tank hard enough to hear the noise. If you had a steel lid I don't see why not.