My brother-in-law and I are redoing a basement bathroom. We cut out an eight foot section of cement floor. Shower and floor drain are completed corroded shut as it was cast iron. We are adding a toilet in this area also. Outlet drain pipe is 4" cast iron. We are cutting out about an 8 ft. section of this and replacing with PVC. Please see attached links to pictures. We have new PVC floor drains for this new section. My question is: does my toilet need a closet bend if it will be located directly over new 4" drain pipe? The vent is located about 5 ft. from toilet.

Find pictures at this link:

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Installing it directly over the 4" will be a problem if your bowl loses its seal which can happen from time to time depending on the flush i.e. a partial flush (someone flushes prior to the tank being filled to the normal flush level). Hope that isn't confusing.

So if I use a closet bend that will take care of any leaks?

Leaks are a function of the way the toilet was installed. The closet ring should be set at a height that allows the bottom of the ring to rest on the finish floor, then the wax ring placed properly so as to not interfere with the flush (particularly on low flush toilets).

srloren

Thanks for your help.

Srloren, I'm confused by your reason of why it might be a problem attaching above the mainline, if the seal leaks, instead of attaching to a closet bend. Please explain.

maybe not a closet bend, but, you WILL need a toilet flange against which the wax will seal to eliminate odor



BOTTOM of said flange sits on top of the finished floor

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Your leak at the wax ring becomes a vent into your bathroom...hope that explains it?

srloren

The floor drain that you have appears to be made of ABS, as it is black. Are you aware that you cannot attach the ABS to the PVC in the normal weld pattern. Do you need special glue. I would recommend getting a PVC floor drain

if there is a wax seal break then sewer gas may seep into the bathroom unless there is a air tight caulk seal around the bottom of the toilet and the two flange connections, but how would a wax seal break behave differently with the toilet connected via a closet bend vs directly on top of a main line via say a combo?

the toilet flange is called a flange because it acts as a flange upon which the wax spreads and seals as opposed to the more 'knife-like' end of a plain pipe

this principle is why the bottom of the toilet flange MUST sit on top of the finished floor establishing the proper 'designed' gap - else a poor extremely fragile seal is created (albeit possibly leak tight for a long time)

the 'outlet' of the toilet's 'horn' should actually discharge lower than and (obviously) inside the toilet 'receptor flange' like a nozzle

the wax (theoretically) is only to prevent sewer gas passage, NOT make a pressure water seal, albeit it 'should' prevent 'splashes' from exiting

think 'GRAVITY FLOW'



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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



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