In general, a waterproofing membrane is a part of the shower floor, the shower walls, and the curb.

Mongo,

Thanks! So I can get away with not doing the floor outside the shower I guess?

"So I can get away with not doing the floor outside the shower I guess?"

Correct. If it's a "typical" shower with a curb, then the wet area that needs a waterproofing membrane will only be the curb and the area inside the shower.

Thank you, Mongo! Appreciate it.

I may go ahead and do it all though for peace of mind, hehe. Tile guy said it's really not that much more work or expense.