Cast Iron Ptrap on remodel

[alex rodriguez]

Hi everyone. I’m located in South Florida. I’ve done a few tub conversion to shower stall before. Always ran into PVC plumbing. Have this one old tub/shower combo that was piped with cast iron pipes. Whole house is. House was built 1965. This ptrap here is not leaking, however the owner does say that they have had random backups with the toilet 1 ft away in the past while the tub/shower was running.
They are converting to full shower stall and want pvc drain. As seen in the pictures I do not have much room under the slab to cut the cast iron. Will be very difficult to cut behind the joint. What is the recommended course of action for updating this ptrap for a shower ptrap. Thank you for your help.

It might be worth noting that the copper supply lines just rusted out last month and the customer had to do a full home repipe through the attic. They have anxiety about the cast iron ptrap deteriorating in the future. Thanks

 

[Jeff H Young]

whats your plan put a shower drain right where the p trap is ? id bust out concrete cut the old trap off , temporarily put a 90 degree fitting on the trap arm pointing up, do a running test. probebly run a snake down that branch, concider running a camera and after all that was confirmed good proceed with extending the trap arm and p trap ( in pvc in florida I use abs in ca) to where the drain center belongs . thats how Id prefer to do it

 

[Sponsor]

 

[alex rodriguez]

Here’s a label of the whole branch. Thank you for your input.
The plan is to leave the shower trap in its same location. They want a linear drain installed towards the front. The trap is very near the vent, how far would you recommend replacing. And also, is there any advisable way without chipping more concrete?

 

[Jeff H Young]

in this case maybe just blast a garden hose down if it takes a good draining call it good. Personally id wack it off the hub but you can remove p trap put a donut and adapt to plastic

 

[Tuttles Revenge]

I would use a string to verify the circumference of the trap nub where it enters that next hub. Determine if its close enough to a size that you can get an all metal clad Mission/Fernco coupler onto. It it is, I would cut that trap off leaving as much of the straight "Pipe" as possible to band onto and then convert to a PVC trap.

If there isn't any usable pipe, then I would remove the fitting from the hub and insert a Donut into the hub and install your PVC trap.

 

[wwhitney]

If there isn't any usable pipe, then I would remove the fitting from the hub and insert a Donut into the hub and install your PVC trap.

Quick comment: using a Fernco underground, you'd need 2" of straight smooth cast iron sticking out of the hub to fully engage the coupling.

Quick question: you are expressing a preference for a rubber coupling over a rubber donut. Is that a general preference (if so why?), or is it based on the situation here where the more of the existing is retained, the better the access and less chance of needing to break more concrete?

Cheers, Wayne

 

[wwhitney]

And also, is there any advisable way without chipping more concrete?

As the concern is that the existing cast iron under the slab may be compromised, you'll need sufficient access to investigate that, e.g. with a camera. And if some of it compromised, you're going to need to chip more concrete to repair or replace the cast iron.

So while this question is understandable, it's only relevant if your investigation determines that all the cast iron is in good enough condition to leave as is.

Cheers, Wayne

 

[Tuttles Revenge]

Quick comment: using a Fernco underground, you'd need 2" of straight smooth cast iron sticking out of the hub to fully engage the coupling.

Quick question: you are expressing a preference for a rubber coupling over a rubber donut. Is that a general preference (if so why?), or is it based on the situation here where the more of the existing is retained, the better the access and less chance of needing to break more concrete?

Cheers, Wayne

Only a jacketed Fernco/Mission band is approved for inside of a building. The 2" versions that have 2 worm drive bands are roughly 2" long and insert only 1" to the stop. If the OP can cut the portion sticking out. Getting a grinder or sawzall with appropriate blade. I think this is the easiest and most sure route.

https://www.supplyhouse.com/Fernco-3000-22-2-x-2-ProFlex-Coupling-Cast-Iron-to-PVC-Steel-or-Extra-Heavy-Cast-Iron

Failing being able to band onto the "pipe" then reeming out the bell is the next best way to adapt. Using a Fernco/Ty-Seal style insert donut/gasket is the next easiest. We always bring the extra heavy duty version along, since cast iron pipe hubs were not standardized.

https://www.supplyhouse.com/Fernco-22U-205-2-Compression-Donut

**Side note**
We are working on a project right now where we are replacing the lead drain piping in a condo. The cast hubs we're dealing with are larger diameter than any i've ever seen and have almost a half inch of gap when we attempted to use the insert donut. I ended up having ABS caulking fittings shipped up and buying Okum and a Polyurethane caulking from Oatey to caulk them in place. Ultimately we found that due to some DIY work on the stack, several of the vertical 4" drain hubs had come apart and we replaced the WYE fittings we were needing to instert.. so we replaced those with No Hub instead.

 

[wwhitney]

Only a jacketed Fernco/Mission band is approved for inside of a building.

Sure, but in the soil under a slab is underground, not inside a building. The roughly 2" long versions are not rated for burial in soil.

Cheers, Wayne

 

[alex rodriguez]

Thank you all. I will try the first step and see how it goes. Will keep you all updated on this project. Hoping the rest of the line is not compromised but I will see

 

[Tuttles Revenge]

Sure, but in the soil under a slab is underground, not inside a building. The roughly 2" long versions are not rated for burial in soil.

Cheers, Wayne

Holy Sheet! We've used them under slab since I've been plumbing.. going to have to send Fernco an email.

I have thousands of these installed under slabs with inspections in dozens of jurisdictions.

Mission Rubber reccommends theirs for above ground. But they do have a 4 worm drive version that is "Recommended for above and underground installations. Easy to install and reuse."

HEAVYWEIGHT Couplings Archives - Mission Rubber LLC

www.missionrubber.com

 

[wwhitney]

Holy Sheet! We've used them under slab since I've been plumbing.. going to have to send Fernco an email.

No email required. This page says that Fernco Proflex are for "for above-ground applications." And the listing standard is ASTM C1460, which is titled "Standard Specification for Shielded Transition Couplings for Use with Dissimilar DWV Pipe and Fittings Above Ground."

Proflex Couplings | Fernco - US

The GO-TO Above-Ground Shielded Transition Pipe Coupling Proflex is a shielded transition pipe coupling that allows you to make pipe connections that are resistant to shear forces, while creating a rigid, long-lasting pipe joint.

www.fernco.com

Misson Rubber Bandseal is the same.

Mission Rubber reccommends theirs for above ground. But they do have a 4 worm drive version that is "Recommended for above and underground installations. Easy to install and reuse."

OK, but that's not a Bandseal fitting. That's listed to ASTM C1540, which is "Standard Specification for Heavy-Duty Shielded Couplings Joining Hubless Cast Iron Soil Pipe and Fittings." I.e. it's a heavy duty no-hub. So you can use it above ground and underground (just like regular no hubs, I believe), but only with cast iron pipe. [Although IIRC the IPC might have some language allowing no-hub fittings for use with PVC pipe underground. Unless the UPC has something similar, that's moot for you.]

The definitely correct shielded underground coupling to use is something like Fernco "Strong Back RC 1000 Series Couplings" 10XX-RC series.

Cheers, Wayne

 

[Reach4]

shower base in concrete

This clever position marking. technique may help positioning the trap.

I don't know if you will have enough space for a trap, since the drain is in-line with the drain pipe.

 

[alex rodriguez]

Quick update: I pulled out the cast iron ptrap using a drill, chisel, and prying out the lead joint. Pulled out the oakum and then the ptrap came right out. Took me about 1-2 hours to diligently pry out all the lead and oakum. Using a fernco donut I am now attempting to secure 2” pvc to the hub. Struggling, but still attempting this step.

 

[alex rodriguez]

Project complete. Thanks for all your advice. I used a fernco donut to secure the PVC to cast iron hub after removing the cast iron ptrap. Was only able to get the PVC into the donut by sanding the bottom 1” of the PVC and lubing with dish soap. Went right in after that, then connecting the PVC ptrap was simple. Thanks for helping me move forward with this remodel

 

[Jeff H Young]

looks great! good luck on rest of job