1 1/2" tub to 2" shower?

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Mikey

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I'm replacing an old tub with a barrier-free ADA shower. The current drain is 1/1/2", and code requires a 2" in the shower. What's the likelihood my local inspector will allow me to retain the 1 1/2" drain for the shower? Aside from being a very difficult conversion, it makes no sense to me (not that that matters). The flow rate when you empty a filled tub is dramatically higher than the 2.5 GPM maximum in my shower, so why the need for a larger drain? (You may have guessed I'm not a plumber. I'm an electrical engineer, and this rule is (to me) the equivalent of requiring a 15A circuit breaker for an old CRT TV, and a 20A breaker for a new LCD.)
 
Probably would better to call your local inspector and ask him. Why run the drain wrong and then have to tear it
out.
 
In usage, drains tend accumulate build up over time. Any dead plumber knows this.
A 2" drain alleviates having to constantly be snaking hair and other build up.
Even then, I have had many customers who need showers cleaned out due to hair build up from long haired occupant use.
So, the rule is designed to minimize headaches. Just ask any dead plumber about his experience.
In practice, copper drains tend to be fairly bacteriostatic and sluff-off build-up (except for hair). I have cut out many 1-1/2" kitchen drain lines from the 50s and they are clean as the day they were installed- no kidding.

I have a 50s bathroom in my home and it is 1-1/2" copper, brass p-trap, copper pipes. I have used it daily for 22 years w/o a clog. The ss top/strainer is just a basic and it does catch a lot of hair. Rarely do long haired people use it.
 
breplum said:
A 2" drain alleviates having to constantly be snaking hair and other build up.
Click to expand...
I've cleaned out a bunch of hair from bathroom sinks and tubs, but it was all caught in the fixture strainers; never had to snake a bathroom fixture. But, your explanation makes some sense; thanks.
 
Shower has no overflow so needs 2" drain to prevent flooding.
 
sawguy50 said:
Shower has no overflow so needs 2" drain to prevent flooding.
Click to expand...
That doesn't compute at all, other than considering that the 2" drain might take longer to fully clog, as breplum suggested. An un-clogged 1 1/2" drain can drain anything a 2.5gpm shower can provide, and the tub overflow is just to prevent flooding when the bather forgets to turn off the taps - has nothing to do with the 1 1/2" drain size, and if the drain line itself is clogged, the overflow won't drain either. Finally, the tub main spigot can flow a lot more than a 2.5 gpm shower, so if anything, the tub should require the larger drain.
 
Wondering what your situation is that you need to pull a permit to replace a bathroom fixture. I have done lots of major updates without permits. I am also an electrical engineer and I do pay attention to codes and follow them for the most part. In general the codes are based on best practices but, in this case, it is really stupid. Of course bigger is better for drain size but 1.5" can handle the flow and hair will clog a 2" drain if you don't use a strainer.
My comment is probably mute as you have already pulled a permit but in the future, think about ways to get it done without one.
 
You seem to be expecting a local inspector and (in every place I have lived in) they don't come out to inspect your work unless someone has applied for a permit.
If you don't have a permit and don't intend to apply for one, there should be no need for an inspection.
Just get the connections right so it never leaks. Then do what you can to make the 2" to 1.5" transition as smooth as possible so hair doesn't catch on it and make sure the drain cover is easy to remove for cleaning.
 
Permit or no permit, I generally try to conform to all reasonable codes, but if one seems unreasonable, I at least like to know why the authority having jurisdiction might think it reasonable.
 
“Reasonable codes”? You mean the ones that apply to “others”? I get that a lot from people who want everyone else to follow the code, but for them, “come on it’s just me”and then they get mad when I don’t agree. It’s not that your shower won’t drain, it’s that your drainage will have to go uphill somewhere to get into that 1 1/2 pipe. Reducing waste lines will require service often. Kinda like “pay me now or pay me later”.plumbers respect that code because we know men far smarter than us figured it out what will work best over the long haul.
 
My box has created many happy clients over 30 years.
 
here is the deal, you are installing a HC shower, the access code on a HC shower is the curb.
[the curb is the thing you step over to enter the shower] SHALL not be higher than 1/2'' above finished floor
this is HC code to be wheelchair accessible.

now, tonight, when you take a shower in your tub. bend over and look at how much water is in the tub as you splash around in the rain drops
 
Yeah, essentially none. Our curb is zero, continuous 1/4" per foot from 3" outside the door to the linear drain, and the entire bathroom is built as a huge Kerdi shower.
 
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