I am thinking of adding a first floor bath in my 1921 house. It would be located between the second floor main bath and the basement half bath so all plumbing is right in line and accessible. It has a 4" cast iron wet stack and my only worry is how do I correctly cut into it to add a toilet and sink drain. Do I have to disconnect the 2nd floor sink bath and toilet from the stack or since I am going to have to add a wye tyin can I just jack enough to sneak the wye in after cutting a section out?
Thanks in advance
Ron

I am thinking of adding a first floor bath in my 1921 house. It would be located between the second floor main bath and the basement half bath so all plumbing is right in line and accessible. It has a 4" cast iron wet stack and my only worry is how do I correctly cut into it to add a toilet and sink drain. Do I have to disconnect the 2nd floor sink bath and toilet from the stack or since I am going to have to add a wye tyin can I just jack enough to sneak the wye in after cutting a section out?
Thanks in advance
Ron

Hi Ron...

This is really all about safety here! Cutting into a stack can be very dnagerous work if you don't take the proper steps to support the stack before you cut into it.

In this case, you would purchase a RISER CLAMP (see picture) and install that tightly to the main stack and then support under the arms on each side of the clamp with 2"x4" studs. Ideally, you would snug the riser clamp up under a HUB joint so the clamp couldn't slide down.

Then you would cut into the stack using a sawzall with an 8" bimetal cutting blade (graphite or diamond sawzall blades do best if you can find them). Do not use the snap or chain cutters in this case as they can crush the pipe or create longitudinal cracks along the pipe which is usually a bad thing! Stick with sawzall.

You would measure the NO-HUB CAST IRON WYE (or sanitray tee fitting if vertical) from top to bottom and then add 1/2" to 3/4" to that measurement. Then mark that measurement on the pipe. Use a piece of paper to wrap around the stack and transfer a straight line around the entire pipe with a grease pen or a permanent magic marker.

The additional 1/2" to 3/4" you added to the length of the fitting is to accommodate a slightly crooked cut and to accommodate the rib in the clamps you will be using to connect this all back together.

You would purchase either cast iron shielded clamps or 4 band no-hub clamps (called husky clamps)... see pictures below. You install the rubbers onto the fitting, roll the rubbers back on themselves and slip the fitting into place. You should slide the clamps on pipe before inserting fitting with rubber sleeves on it.

Then just flip rubbers back so they join the pipe and then slide clamps down and tighten up clamps as needed.

Then you want to make a transition from cast iron to 3" pvc using a shielded transition clamp (cast iron to pvc). All these materials are sold at your local plumbing supply house.

Pipe this so the the lavatory pipe acts as vent for the toilet (means pipe needs to be 2" to lavatory) and then run that vent upstairs and connect it at about 48" off the finish floor or run vent into the attic anc connect into 2" vemnt up there.

Let me know what you think...

MARK

Hey Ron... I see you posted a pic. While I was typing...

Give me a few minutes to work this out for you... :)

MARK

Check out my pic. Below and see if it makes sense with what I wrote above. Also want to add a 2" cleanout in the lavatory drain if possible.

Use a 4"x3" cast iron sanitary tee fitting here.

The vent can connect in the attic or at the bathroom on 2nd floor at 48" or so off the floor (I did not draw it like that).

Let us know if this makes sense.


.

Mark
Thanks so I need a tee/wye for below first floor that will connect to a separate vent and toilet drain and separate vent runs parallel with stack and has to tie back into it in the attic or halfway up second floor above 2nd floor toilet tyin? So I need to open the stack in two places?

Is there any issue with the kitchen sink being unvented? I read elsewhere on this site about that being code... is it?

Hi Ron...

Are we discussing a FULL BATH on 1st floor? Drawing only showed sink and toilet? Let me know.

And Yup!. need to connect into stack in attic with 2" vent or can cut this vent in at 48" off finish floor of 2nd floor bathroom. You also need to cut a sanitary tee fitting in the basement... so yes, two cuts into the stack... or you could penetrate the roof with a new 2" vent if you find roofing easier than plumbing.

You did not mention the kitchen sink.. thought it was existing. The kitchen sink definitely needs a vent. The 1.5" vent could connect into the new sink vent at 48" off the finish floor of the first floor or it can connect in vent system in the attic. You may also be able to install an AAV (air admittance valve), but it would need to be accessible under the sink and it would need to be approved by codes enforcemnet before installing it.

Let me know if need more...

MARK

As Mark said, you will need vents for toilet and sink.

I am not sure what anything is anymore... need a more specific drawing here... ;)

Vents should be 2" from the toilet and at least 1 1/2" from sinks. You could use AAV vents if allowed in your area.