Connect PVC to Cast Iron

[md2lgyk]

I need to move an existing toilet about a foot. The DWV piping is cast iron. My first thought was to break the drain pipe, replace the existing flange with a PVC one in the new location, then connect the two with PVC pipe and a Fernco coupling. On further consideration, I'd like to run PVC all the way to where the drain connects to the soil stack (only about 4 feet or so). Is there a rubber gasket of some sort that will allow me to connect a PVC drain at the hub of the sanitary tee in the main stack? What is it called?

[LazyPup]

Fernco makes a rubber gasket for that purpose but i dont really care for them. I prefer to clean out the hub thoroughly, insert the PVC into the hub, then pack the hub 1/2 full with oakum and fill the remainder of the hub with plumbers expoxy in the same manner as lead was originally used.

The plumbers epoxy is a two part putty type epoxy, one part white and the other part black that you must knead together until is is an even grey color to activate the catalyst and resin.

You can buy the plumbers epoxy at Lowes, Home Depot and most hardware stores.

You can buy oakum in nearly all hardware stores. The make two types, plain oakum and oil impregnated. I prefer the oil impregnated type when i can get it.

Oakum will look like a piece of frayed hemp rope about 1" in diameter and usually comes in lengths of 2 to 3ft. You wrap it around the pipe and pack it into the hub.

[md2lgyk]

Thanks. I did do some checking on the Fernco site and believe I found what you're talking about, though they were called doughnuts and not gaskets. Anyway, your solution sounds better. The Fernco site talked about how the size had to be just so and I'd need to know who the pipe manufacturer was.

On a related subject, did there come a time when cast iron was still used for DWV/sewer piping but lead was not? My house was built in the early 1960s and was originally on a septic tank. All the original DWV piping (that I can see anyway) is copper. When the house was connected to city sewer some years later, cast iron was used. The pipe hangs on the wall about three feet above my basement floor, and the joints have a rubber gasket of some sort. Only the joint between copper and cast appears to be leaded.

[LazyPup]

To put it all in perspective the fernco is properly called a "Donut Gasket"

In the early 80's the construction industry as a whole began to have some serious concerns about the use of lead or lead bearing materials. These concerns ranged from lead based paints, lead masonary anchors, lead piping, lead solder in water pipes and cast lead in soil pipe joints and sheet lead shower pans.

While the changes did not all occur at any specific time, all of the building codes have been slowly ammended to reduce the amount of lead bearing materials. By example, it is currently illegal to use any lead bearing solder in the potable water system.

While not all lead products have been specifically outlawed, there is a Federal moratorium to reduce or eliminate the use of lead in residential construction altogether. By example, in my jurisdiction while it is common to find field formed lead closet bends we are not permitted to repair them. In the event a formed lead closet flange is found defective we are required to remove it and replace it with PVC.

In response to these changes the manufacturers have come up with some very innovative solutions.

They currently make hub type vitreous clay and cast iron soil pipe that has a rubber gasket cast right into the hubs. The more commonly used cast iron pipe in new construction is "Hubless cast iron soil pipe" The hubless cast iron pipe has a groove cut around the outside pipe wall about an inch from the end. The couplings then have a rubber gasket with a raised ridge that fits into the groove, a metal band wrapping the coupling and two ratcheting hose type clamps to hold it in place.

While lead joints are no longer permitted for new residential construction they are still required in some specialized type drains in commercial work such as "Explosion proof drains" in a chemistry laboratory in schools, colleges, hospitals, research facilities or commercial laboritories.

The "Hubless" type connectors are not practical for homeowners or DIY applications because they require so very expensive specialized tools to field cut the cast iron pipe to lenght and grind the necessary mounting groove on the end of the pipes. The alternative is the rubber couplings such as those made by "Fernco corp"

When selecting Fernco couplings you will note that they indexed by the type of pipe, I.E> PVC & ABS, Copper (CU), Cast Iron (CI) thus a fernco coupling used to join PVC to cast will be labelled PVC x CI. The indexing is to insure the inside diameter of the coupling will be the appropriate size to fit the outside diameter of each respective pipe material.

[md2lgyk]

Thanks for all the great information. Though I've been dabbling in it as a DIYer for almost 30 years, I'm only now appreciating how complicated plumbing can be and how much the professionals have to know. I do remember when lead solder was outlawed for potable water systems. I went to buy some some for a project and was told I had to use this "new" stuff (which of course cost more).

[LazyPup]

I shall never forget my first night in the college apprenticeship classes. I had previously been certified an a High Pressure Boiler operator and an Residential and Commercial AC & Refrigeration Tech, as well as having worked maintenance for a number of years, so I felt pretty confident that I knew my way around plumbing and piping fairly well.

Most of the students in the class i started in were in there third year of training and as luck would have it, they were having a quiz the nite I entered the class.

The instructor handed each student a set of house plans and told us to lay out the DWV piping system, indicating all pipe sizes and location of necessary vents and cleanouts. The only information on the prints was fixture location and the site plan showed the location of the septic tank. After two hours of staring at that print I had a total of the main sewer line from the house to the septic tank, and even then I did not have the required main cleanout. At the time i thought that instructor was being a real hard a** but I soon learned that in new construction that is exactly what a plumber is given to work with. We get the building print showing the finished location of all sinks, appliances and fixtures, and it is the responsibility of the Master on site to lay it out.


Pure lead solder is still available and may be used for other purposes. I personally use it quite often to dabble at leaded glass projects and copper sheetmetal projects.

Although it has not yet reached national level, there is a strong movement amongst many local governing authories to outlaw the use of petroleum based acid soldering flux in exchange for the water base flux.

Fortunately for me, i began my copper pipe soldering career in the refrigeration trade where everything must be silver brazed and must be gas tight to the molecular level. With that background soldering copper water pipe was a cinch, but even with that background I find water base flux a lot more difficult to work with.

[md2lgyk]

Just reinforcing my point about how much you pros have to know.

On a related note, I've seen your post and illustration elsewhere here about notching joists. I suppose in trying to move this toilet even such a short distance I may cross a joist. The house is perfectly square, with a weird roof line, so I can't tell until I open the floor which direction the joists run. Assuming the worst and I would have to cross a joist, is that the end of my project? Obviously notching for a 3-inch toilet drain won't meet the acceptable criteria in your illustration (unless the joists are 2x12, which I doubt). Or can I sister the joist with a 2x4 on each side and make it work?

I guess even if that's possible it would depend on where in the joist length the notch would be? Given the present toilet location (against an outside wall), if the joists run one way it'll be near the center, and if they run the other way it'll be near the end.

[kactuskid]

There are joist reinforcers that you can purchase, I've never seen them in the stores, but this website sells them.

http://www.metwood.com/joist_reinfor...ct_details.htm

[LazyPup]

Extending a 3" waste arm can present a number of challenges.

The maximum length from the trap toilet flange to the vent stack may not exceed 12' unless an additional auxillary vent is provided.

The codes have tables that list the maximum notch or boring specifications.

A 2x10 can be bored to 2-1/8" providing the edge of the hole is not less than 2" from the edge of the joist.

In some jurisdictions the holes may be larger if the joist is sistered (Two joists side by side), but the sistering must be for the full lenght of the joist.

The metal reinforcing plates shown in the website Kactus posted is for engineered wood I beams and are only acceptable with the approval of the I-beam manufacturer or an architect.

[kactuskid]

I'm pretty sure those enforcers are good for engineered I beams plus solid wood joist. If you take a look on the link in their gallery showing applications, there are pictures of it being used on normal solid wood joist. It's a pretty cool device.

Here's a link directly to it.
http://www.metwood.com/joist_reinfor...lery_frame.htm