Do I need to vent a walk in shower that is replacing a tub/shower combo?


I ripped out a 30 x 60 tub/shower and am replacing with a 34x 60 walk in shower (prefab fiberglass pan). The plumbing is currently a 2" drain that tees into a 1.5" tub drain and 1.5" tub overflow drain. My plan is to cut off the t and replace with a 1.5" elbow connected to the shower drain. Will this work and will there be any venting problems? I.e. is the venting already handled by the existing plumbing (which is below concrete slab I can't see).
thanks!!
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snipped-for-privacy@gmail.com wrote:

The 1 1/2" P-trap for the tub must be buried in the slab too. Right?
The vent connection (if any) for the trap is downstream from the trap outlet, so anything you do upstream won't affect it.
It will probably work just fine, even though 1 1/2" is considered a bit small for shower drain.
One thing you might consider is placing a TEE where you make the connection, instead of an EL. In the top of the TEE, put a cleanout Plug so you can get a snake in. It may be very difficult to snake thru the trap from the shower drain opening.
Jim
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Great feedback Jim thanks. Maybe you (or someone else) can help answer this follow up. Why is 1.5" good enough for the drain pipe when it's a combo tub/shower, but a 2" is required when it's a dedicated shower? It seems as if a 1.5" is good enough in the first scenario it should work in the second. Is this just an overly conservative code issue?
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snipped-for-privacy@gmail.com wrote:
<SNIP>

HaHa! My opinion is it's overly conservative. Either that or, maybe, 1 1/2" was always too small...
Jim
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What happens if a standalone shower drains slower than the showerhead produces water?
What happens in a bathtub?
--Goedjn
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On Feb 16, 6:25 pm, snipped-for-privacy@gmail.com wrote:

Nah it doesn't sound like you are interfering with the existing vent so don't expect a problem there.
Code however calls for a 2" drain for showers but for the life of me with all the low flow showerheads in use I doubt you really need more than 1-1/2
I just built a tiled enclosure on the same sized pan mostly because the big box couldn't find a set of fiberglass walls that were not cracked.
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