No hub underground without replacing cast iron in wall

[Squalor]

I have 1963 house in southern California, the 4" cast iron main waste line needs to be replaced under back to back bathrooms. Both bathrooms have tile midway up the wall. I am reluctant to remove the tile to replace the cast iron pipes in the wall because it would require a remodel of one of the bathrooms. I am thinking of just opening the floor not the wall. Will the cast iron coming up through the slab last a long time or should I open the wall and replace the cast iron in the wall while I am at it. I would hate to have to open the floor again but I don't want to remodel the bathroom at the same time.

 

[Terry]

The pipes in the wall are your venting for the plumbing fixtures. It would be very difficult to just replace the horizontals in the slab and still make connections to the walls. Maybe not impossible though, so much depends on how yours was done. And yes, normally the pipes in the wall are better for the venting, though some of the old galvanized drain lines could be in pretty poor shape too.

 

[Sponsor]

 

[John Gayewski]

I have 1963 house in southern California, the 4" cast iron main waste line needs to be replaced under back to back bathrooms. Both bathrooms have tile midway up the wall. I am reluctant to remove the tile to replace the cast iron pipes in the wall because it would require a remodel of one of the bathrooms. I am thinking of just opening the floor not the wall. Will the cast iron coming up through the slab last a long time or should I open the wall and replace the cast iron in the wall while I am at it. I would hate to have to open the floor again but I don't want to remodel the bathroom at the same time.

It's highly dependent on conditions. No way to tell how good of condition it's in from here, so there's no way tipp know how long it'll last. If your replacing pipe you might as well go for it in my opinion.

 

[Squalor]

There is 2" cast iron coming through the floor/slab to the sinks, shower, tub, probably to the back to back toilets, probably 3" or 4" (I can't see that section). It then transitions to galvanized pipe for the vents. The idea is to no hub to the 2" cast iron below slab. The galvanized pipe in the wall looks ok. I can see most of it because there is an outside access panel for the tub, I remove a medicine cabinet and vanity and can see in the wall in those locations.

 

[John Gayewski]

There is 2" cast iron coming through the floor/slab to the sinks, shower, tub, probably to the back to back toilets, probably 3" or 4" (I can't see that section). It then transitions to galvanized pipe for the vents. The idea is to no hub to the 2" cast iron below slab. The galvanized pipe in the wall looks ok. I can see most of it because there is an outside access panel for the tub, I remove a medicine cabinet and vanity and can see in the wall in those locations.

We do similar stuff all the time. It's just based on a per pipe condition thing. We replace the things we don't think will last.

 

[Squalor]

Then, the plan would be to open the floor and if the cast iron going through the floor looks bad, open the wall at that point, correct? What are the recommended no hub fittings for this purpose?

 

[John Gayewski]

Under ground we don't use no hub bands. We use bell and spigot service weight (or extra heavy) cast iron and rubber gaskets.

They do make no hub bands for underground but they are special and expensive.

 

[Squalor]

I would like to connect the cast iron to abs underground. Can you please give me a link to something that would work well for this purpose. Even if I replace everything in the wall. There is a cast iron line coming in horizontally underground from a kitchen sink and washer.

 

[John Gayewski]

https://www.grainger.com/product/53UE64?ef_id=Cj0KCQiAraSPBhDuARIsAM3Js4oa8WKZwDDCg-MEIDhaLD1SWAY3LDbr-Mvm1tD25x6cw0EoTpZ_ymUaAjOgEALw_wcB:G:s&s_kwcid=AL!2966!3!496359973330!!!g!469890691406!&gucid=N:N:PS:Paid:GGL:CSM-2295:4P7A1P:20501231&gclid=Cj0KCQiAraSPBhDuARIsAM3Js4oa8WKZwDDCg-MEIDhaLD1SWAY3LDbr-Mvm1tD25x6cw0EoTpZ_ymUaAjOgEALw_wcB&gclsrc=aw.ds

This isn't exactly what I was talking about and you'd have ri find the right size, but this would be ok I believe.

 

[Squalor]

There are these

https://www.lowes.com/pd/Fernco-2-in-x-2-in-x-2-28-in-dia-Shielded-Specialty-Coupling-PVC-Fitting/1000075337

Lowes says for underground but Fernco seems to say for above ground and there these that Fernco says for below ground

1056-22RC - Fernco 1056-22RC - 2" x 2" Strong Back PVC Shielded Coupling (Connects Cast Iron, PVC, Copper, Steel or Lead)

Fernco 1056-22RC - 2" x 2" Strong Back PVC Shielded Coupling (Connects Cast Iron, PVC, Copper, Steel or Lead) - 2" x 2" Strong Back PVC Shielded Coupling (Connects Cast Iron, PVC, Copper, Steel or Lead) <br><br> <b>Connection Type</b> <ul><li>Underground <li>Cast Iron connecting to Cast Iron...

www.supplyhouse.com

 

[Squalor]

What is the best way to bed the new pipes to prevent shifting and the couplings slipping? Has someone heard of pouring mortar (not concrete) (in a way grouting the pipe in place) around the pipe up to half way the circumference? A friend that does large commercial pipelines suggested it.

 

[Breplum]

The 'Strong Back' are excellent. You stated 4" ABS to CI, the Mission CP44 or equal is a two band, shielded coupling that will work for that transition.
Not over excavating is the best practice to prevent settling, in mud we've poured dry bags of concrete under sections of cast iron. "Road base" quality gravel, when well compacted is what sewer dept wants in over-excavated situations.
We never do 4" drain work in close proximity situations in ABS, just not enough ease to work with. CI is so much easier to manipulate and fit.

 

[Squalor]

Thank you for the feedback. I am working on replacing the 4" cast iron main waste line under slab with abs. The couplings are for connecting abs to the CI that I will not be changing depending on what it looks like after a get access to it, those connections will be 2" and 3". There might be a muddy section where the CI has been compromised.