Tub drain without a trap -no room

[DIYsteve]

Folks, I started smelling sewer gas in the bath in our basement bathroom. I identified the source as the tub drain. I crawled into the cabinet on the floor and discovered there’s no trap for the drain, and it appears it wasn’t installed because there is no room for one. Are there any alternatives to traps, that can be installed in super close quarters? Some kind of gas-effective check valve, maybe? I have under seven inches laterally, and maybe 5” on the vertical to work with. The biggest issue is the lateral confinement between the actual tub drain and a tee it runs straight line to.

 

[Zanne]

Can you get any other pics of the area so we can see where the floor is? It looks like that's the overflow on the left and drain on the right, but I can't see below that to see how much space you have to work with.

 

[Jeff Handy]

Looks like you have enough room vertically.

If not, you can get low profile p traps.

The horizontal room looks plenty long.

If you are stumped, hire someone with experience.

 

[JG plumbing]

Looks like there is enough room to me.

You can also make a trap.

Definitely not a check valve.

 

[Zanne]

Wait, is that the tub shoe on the bottom? For some reason I thought this was from a different angle and it was the overflow. If it is the tub shoe you can get a "direct drain". @frodo linked one to me before. Instead of a tub shoe, the drain comes straight down, the overflow instead of the opposite way. The P-trap would be directly under the tub drain.


My concern is how notched that wood is. If it's load-bearing it might need a plumbing box built in to reinforce it. Or is it sitting directly on the ground? I still don't like how big the notch is even in that situation.