The downside of floor drains is that drains are bidirectional and drain backups come out of the lowest point. That's probably ok in a laundry room or bathroom, but wouldn't be nice in other rooms.

Could you route the drains to plumbing lower down in the system? I'm picturing all wet rooms draining to a funnel in the basement via a dedicated gravity drain system. He did say 'custom home'....

Unless you're running a pumped drain system, all of your drains must route to plumbing lower down.

If upper floors' floor drains route to lower floors before joining with other plumbing on the lower floor, that would prevent backups from rising to the upper floor drains (unless their particular pipe was clogged, which should be unusual in a residential floor drain). But you'll have this issue at least at the lowest level of the dwelling.

Basements are not common where I've lived, but where present in custom houses, they tend to be fully finished and plumbed and then they'd have floor drains too.

In some buildings elsewhere, I have seen a less finished basement, with only laundry and a slop sink... That slop sink may be where a backup from the lateral to the utility sewer (or septic system) would come out. But that's not a common look for a fully custom home.

A lotta slop sinks are just washing machine drains. Lets your machine pump as quickly as it wants without needing to a separate high-flow drain. And buys you more litres of backflow before its a real problem. Tho some washing machines can pump up quite a few feet if needed.

Lived in an apartment where the front-loader managed to pump a sock into the high-flow drain where it got stuck. That was fun...

(Also had a front-loader break it's door seal, also a lot of fun...)

Many parts of the US don't have basements. The lowest point is inside the slab, so drains are relatively constrained.

Even if there is a basement, a lot of homes will have a gravity sewer line that is above the level of the basement floor, and utilize ejector/sump pumps for water below the elevation of the sewer.

Backflow preventers are common in some areas. But you're kinda in the dark if it's activated and shouldn't run anything down any drain on your side.

Not only common, but required by building code.

Maybe in newer construction, but in older (ie: before flood maps were a consideration, good drainage, grading, storm sewers), generally not.

What's even more problematic is that new North American homes are often constructed with a washer/dryer "conveniently" placed near a bedroom, typically on the upper level, and yet, they are still installed without a drain.

Drain aside (which, AFAIK, would be required by code where I live) I'd love to have the washer/dryer located near bedrooms. Having the laundry off the kitchen, garage, or in the basement creates needless make-work transporting clothes across the house. I don't ever disrobe or dress outside my kitchen, garage, or in my basement. (It would make more sense if the laundry backed-up to the bedroom closets.)

Wouldn't the noise and vibration get tiresome quickly? Or are new machines quiet and stable enough that it's not an issue?

We usually do laundry on the weekends, during the day. It's actually more annoying in the basement, as that's where the familyroom/TV are located (and the wall between the W&D and family room is just single-layer drywall, with the W&D right there).

My washer and dryer are in a washer-and-dryer-sized closet in the hall near my bedroom, but I guess the noise insulation is good enough that I don't hear it when it's running at night.

I’m relatively sensitive to noises (analog clocks are a hard no-go because of their soft ticking; it’s infuriating trying to sleep somewhere that has them). But I barely hear our dryer when it’s running at night, and it’s just on the other side of our bedroom wall. As long as we aren’t doing a load with lots of hard buttons and things (which make a louder clinking sound when tumbling) the dryer is totally fine at night.

The washing machine, not so much. The water lines and spin cycle aren’t particularly loud, but they’re loud and distinct enough that it’s too loud for me at night.

I've got a 12+ hour window every day in which nobody is in the bedrooms.

Concur. I live in a 1970s townhouse with a basement laundry room. It's annoying to cart loads of laundry down 2 levels and back up again.

I'd love to have an upstairs W&D, but I wouldn't install one with a secondary drain pan.

I have a laundry up stairs. However a drain must be installed in my area to meet code.

>That's in fact a feature I would desire in every room of a custom home.

Some reasons I would not want this is: need to pour water in periodically to keep the trap from drying out and the risk of a sewage backup covering every room in literal shit.

“literal shit”? Check the code in your area. The toilet outlet goes into 4” pipe straight to septic, not the 2” drain pipe.

The vast majority of homes in the US use a public sewer versus a septic tank.

I believe there's a regulation here that requires a drain in the floor of laundry room here in Denmark, but the same isn't the case for kitchens, so a dishwasher can still do a lot of damage.

It is really weird that for all the smart crap manufactures want to stuff into appliances, leak detection isn't particularly high up on the list. It can't really be because it's hard to do, leak detectors are often one of the earliest sensor types available for new smart home kits.

The question I guess is reliability of the leak detectors themselves. Will the detector fail more often than the actual unit leaks?

TIL: A secondary drain often isn't required by code (in the US). I'm also shocked by this, seems obvious, especially for a machine that's above ground-level.

Laundry rooms here in Japan (or rather, bathrooms that have a space for a laundry machine, usually next to the sink) are built exactly that way: the drain is in the floor, under the machine. It's honestly bizarre that this is not normal in the US.