We have a shower in our master bathroom with a bathtub right next to it. My daughter took a shower up there and the next thing you know she was standing in three inches of water and water is coming up through the bathtub drain.

Is it common for adjacent tubs and showers to share a trap? We are probably dealing with a hair/soap scum clog.

Is it a do it yourself job to clear that clog? Would plunging work? Or is it time to call a pro? For a pro, is it a complicated job?

Thanks.

It would be faster and easier for you as the homeowner to hire a pro to clear the shower drain. The lines don't share a trap, but they do connect before the main stack. By the time an average person rents the proper equipment, they could have paid a large portion of the professional drain cleaning and it will be done quickly, more reliably and safer. If you already knew how to clean a drain, I would say to rent a machine, but since you don't, I would call a pro.

They are not suppose to share a trap, but normally share a vent. At the base of the vent stack is where I'd suspect the clog to be.

I'll call a pro. If the clog is at the bottom of the vent stack, can that be cleared from the bathroom? Or needs to be roof?

the clog is not at the bottom of the vent stack. if done properly the vent connection should be between the two fixtures. or each fixture has its own vent.

When faced with a clog you can try some of these methods to solve your problem:
Pour boiling water down the drain. Add salt water to it.

Secondly,you can use baking soda and vinegar into the drain together. Allow the combination to foam for a few minutes and follow up with boiling water.

Try a closet auger, which is a smaller type of drain snake. It's a long, thin tube, often with a hook or bristles at one end. Feed it into the drain. Hopefully, the hooked or bristled end will grab and remove the clog.

Baking soda and vinegar makes a good volcano for a school science project, but does NOTHING for a drain line. Have you REALLY ever tried to insert a closet auger into ANY sink drain?