Shower Drain Connect To Brass Pipe?

[Jeff H Young]

OK.. Looks like we have an exemption to the 2" absolute minimum shower trap size in Washington state.

WAC 51-56-0400
408.4 Waste Outlet. Showers shall have a waste outlet and fixture tailpiece not less than two (2) inches (50 mm) in diameter. Fixture tailpieces shall be constructed from the materials specified in Sec-tion 701.1 for drainage piping. Strainers serving shower drains shall have a waterway at least equivalent to the area of the tailpiece.
EXCEPTION:
In a residential dwelling unit where a 2 inch waste is not readily available and approval of the AHJ has been granted, the waste outlet, fixture tailpiece, trap and trap arm may be 1-1/2 inch when an existing tub is being replaced by a shower sized per Section 408.6(2). This exception only applies where one shower head rated at 2.5 gpm is installed.

Cool it sounds fair to me I was guessing it might require AHJ approval , we typically have 2 inch nearby but not that fun to change out. but those that have worked outside of new construction have likely fudged rough in on a shower .

 

[Khb333]

Ok, I got the old cast iron trap out. So, does it matter where I locate the trap? If I put it back in the same spot it will be about 20" away from the new shower drain.

 

[Sponsor]

 

[wwhitney]

Generally optimal to put the new trap under the shower drain, with 1/4" per foot slope on the trap arm. However, you should determine where the trap arm is being vented and confirm that with the extra length (and rise) it will still be vented before falling one pipe diameter (1-1/2").

Cheers, Wayne

 

[Terry]

Normally within 42" to venting. With 1/4" per foot rise.

 

[wwhitney]

Normally within 42" to venting. With 1/4" per foot rise.

Right, that's the UPC rule. If the OP is subject to the IPC, they allow the full 72" that is possible with perfect 1/4" per foot rise/fall.

Cheers, Wayne

 

[John Gayewski]

Ok, I got the old cast iron trap out. So, does it matter where I locate the trap? If I put it back in the same spot it will be about 20" away from the new shower drain.

20" elevation or horizontally? You can do 20" of elevation but you'd want to get it directly under the shower drain. If needed you can offset with 45's if you are off a little, but 20"is too much

 

[Terry]

20" elevation or horizontally? You can do 20" of elevation but you'd want to get it directly under the shower drain. If needed you can offset with 45's if you are off a little, but 20"is too much

Good point, I forgot that he was replacing a deep tub, and long verticals can siphon traps.

 

[Khb333]

Thanks for all the good info everyone. I've attached a dwg of my proposed shower. I'd have to bust out more slab (house was built in 1960s they didn't skimp on concrete) to put trap directly under the center located drain. Can I put the trap 12" away from drain, where I have busted out slab already? thanks.

 

[Tuttles Revenge]

Thanks for all the good info everyone. I've attached a dwg of my proposed shower. I'd have to bust out more slab (house was built in 1960s they didn't skimp on concrete) to put trap directly under the center located drain. Can I put the trap 12" away from drain, where I have busted out slab already? thanks.

2" trap arms can be as long as 60"

 

[wwhitney]

2" trap arms can be as long as 60"

But the OP was asking about putting a horizontal offset between the shower drain and the trap, not downstream of the trap.

As to the question, it would be allowed, but is a definitely worse solution, so you should break out 12" more of concrete to avoid it.

Cheers, Wayne

 

[Tuttles Revenge]

But the OP was asking about putting a horizontal offset between the shower drain and the trap, not downstream of the trap.

As to the question, it would be allowed, but is a definitely worse solution, so you should break out 12" more of concrete to avoid it.

Cheers, Wayne

I read that he's wanting to extend the trap arm so that his trap will be centered directly in the center of the shower since he's already removed the trap from where it was setup for a tub. - best option

Or is the question whether he can leave the trap in place at the wall and offset the tailpiece to the center? - Not best option

Or am I completely off base and I should just get ready for the weekend and forget all this plumbing stuff. -- even better option.

 

[wwhitney]

I'm responding to this part of today's opening post: " I'd have to bust out more slab (house was built in 1960s they didn't skimp on concrete) to put trap directly under the center located drain. Can I put the trap 12" away from drain, where I have busted out slab already?"

The answer is you could do that, but the better choice is to bust out more slab.

Cheers, Wayne