HerHusband wrote:
I have lived both in Australia and in Taiwan. In both countries,
bathroom floors had drains to avoid serious flooding in the case of
overflows. The bathroom floor drain in Australia even dealt with the
problem of blockage of the regular drains/sewers: the floor drain went
straight out through the wall above the ceiling of the lower story and
had an angled flap to prevent drafts but allowed the water to escape.
Why have I never encountered such in US bathrooms?

From a practical standpoint, it adds a lot of cost and complexity to the
construction of the bathroom.

We built a "european style" curbless shower in our master bathroom. I had
to plan for this during the framing stage so I could frame the shower floor
lower than the rest of the house floor. This also entailed adding
additional footings to support the transition in the floor structure.

Then we had to install the shower drain, and build a slope with mortar into
the floor so water would run towards the drain. After that came the
waterproofing membrane and tile.

We LOVE our large open bathroom. No shower doors or curtains, plenty of
room to move around, it's easy to clean and mop the entire floor down
without worring about leaks, and far fewer problems with mold and mildew
with the better air flow.

However, it's a lot more work to build than slapping down a sheet of
plywood, and sliding in a ready made tub/shower unit.

Anthony
Thats a common thing you see in Japanese bathrooms with relatively new
construction. They actually use a one piece unit that is fabricated
offsite. The first time I saw one I thought that is the way a bathroom
should be built because it is so practical and easy to maintain.