New shower stall drain is larger than existing pipe.

[Mikerios]

I am remodeling an older building, Much of the drain system is built into concrete. The drain system is 1-1/2".
I need to replace the shower stalls, but all the stalls come with a 2" drain. But I know it is not OK to reduce the pipe size in a drain system. How can I solve this problem?

 

[WorthFlorida]

You can replace the drain assembly at the shower base with a 1.5" drain. Going from a larger to smaller pipe after the trap is what is prohibited.

 

[Sponsor]

 

[Tuttles Revenge]

What the UPC says is that it is OK to install a shower which normally requires a 2" drain in a location where you are changing the tub to a shower provided that only 1 showerhead is operable at a time. Most inspectors will want a Bushing into the drain body itself, but I like to use a reducing coupling which is later more readily upgraded to 2" pipe if the place is ever re-piped.. In your case under a slab.. do whichever is easiest.. but the reduction should occur on the vertical before the trap.