Elevated shower pan for basement BR - max height of threshold
I am adding a shower to the basement Bathroom. What is the maximum height recommended from the floor to the shower's threshold?
The basement floor is concrete slab. The main waste pipe exits the house about 15' from the shower drain. The waste pipe is about 4" above the concrete floor. That is, it exits thru the foundation wall, not the floor.
Solution #1. We built a platform for the shower pan that is 6" above the concrete. That 6" accommodated the drain. Tests with water from the hose indicate it drains well.
However, when the shower pan is installed its' base and threshold added 6" more to the step up into the shower. The pan itself added 3" and the pan's threshold added 3".
So, to step up into the shower, one must raise one's foot 12" from the floor. Is that too high?
There are two other alternatives:
2. Another approach is to jackhammer the concrete slab and install waste pipes to a new sump pump. The plumber estimated the cost at $3,000 to install pipes from drain to the sump pump and connect to the waste pipe.
3. Elevate the Bathroom floor 4" to 6", placing a step into the BR. Then, the step up into the shower is diminished to 8" to 6".
Thank you for the benefit of your experience.