Replacing old vent stack.. need help.

Hey guys. I have an older house, one that has an old cast iron vent stack.. I am remodelling my kitchen, and the vent comes up directly into the middle of my kitchen. They boxed it in originally, but I want to open the wall up, so to do that, I need to relocate my vent stack. I have attached some pictures on the issue, and hope that I can find a resolution.

So.. the solution is this: It's currently 4" cast iron all the way up to the roof.. what I want to do is remove the cast iron and replace it with 3" pvc, so it will fit into my wall cavity. As you can see in one of the pictures, somebody already forked into the cast iron 'T' with PVC for the new drain system in the bathroom above.

Above this room is the bathroom, in which the wall behind the toilet was built out to conceal the pipe. I had to do some drain work to the toilet, so that wall and pipe is already accessible, and it continues up into my attic, where it attaches to the stack on the roof, so I can access all of the cast iron to pull it out.

My question is, how can I relocate the pipe back into the wall. If you can make out the picture pretty good, there's about 5" between the back of the opposite wall and the start of the cast iron pipe. When they ran it, they didn't go through the top and bottom of the studs in the wall, they laid the pipe by cutting a hole in the floor in front of the stud (Essentially the wall would be behind the pipe).

I was considering breaking the cast iron off from the basement all the way up, and replacing it all with 3" pvc, but I am stuck trying to figure out how to move the pipe back some more. I am wondering if they make low clearance elbows, or some sort of adapter that I can attach that will divert the pipe back 5" without having to bring the enclosed wall out some more.

What do you guys suggest I do?

The catch is.. the pipe can't simple be moved back up in the attic, because the upstairs walls were framed around the pipe correctly, and if I move the pipe in the bathroom back I will have to cut into the back side of my closet wall, so the shifting of the pipe is going to have to be done on the kitchen level. (The ceiling is currently 10 feet high, but I am putting in an 8' drop ceiling so there is ~ 2 feet of clearance to work with, plus the room between the floor joists.

The below pictures were taken from the kitchen, looking up at the floor of the bathroom above. This is where all the pipe work needs to be done at.

I’m no expert but I have the exact same thing running inside my kitchen wall and almost exactly the same being built outside the wall. Must have been a common practice back then. Are you sure it is just a vent stack? Is it also the waste pipe?

In my case the floor above wasn’t well supported and the beam in the basement and stone wall were massive so I built a new wall in front of the old studs and the pipe falls in there. I gave up a little floor space so I wouldn’t have to think about moving the pipe.

I know that’s not the answer you were looking for but the pros should be along soon.

If this is an outside wall the foundation below might have been a problem for the first installer.

bud16415 said:

I’m no expert but I have the exact same thing running inside my kitchen wall and almost exactly the same being built outside the wall. Must have been a common practice back then. Are you sure it is just a vent stack? Is it also the waste pipe?

In my case the floor above wasn’t well supported and the beam in the basement and stone wall were massive so I built a new wall in front of the old studs and the pipe falls in there. I gave up a little floor space so I wouldn’t have to think about moving the pipe.

I know that’s not the answer you were looking for but the pros should be along soon.

Click to expand...

It is also the waste pipe too, the cast iron 't' that comes in at the top of one of the pictures (that somebody glued PVC into), is where the drains from all the appliances upstairs drain into (They all come together in the ceiling of the kitchen at various points into a 4" pvc pipe that is reduced into a 3" pipe and glued into the cast-iron T fitting). From the T up, it's strictly a vent stack.

What you described you did is exactly what I just tore down, and what I am trying to avoid. This is a wall that a row of cabinets is going to go on, and the end of the wall has a doorway leading to another room, so bringing the entire wall out doesn't really help, and will most likely make things worse. Before they only boxed in around the pipe and made a small laundry shoot next to it, so there was an approximate 3foot by 5 foot notch INTO the room, making it impossible to use that entire wall.. Here is how it looked:

|Nevermind, the forum formatting is removing the extra spacing on the diagram I tried drawing

Click to expand...

Farthest lest | and | is the doorway, the 'x' is where the vent stack is at. I want that wall to be flat so I can line a row of cabinets on it, and at least use the darn wall.

unfortunately, it's not on an outside wall. It comes into the basement at about 3 feet from the foundation wall, and goes straight up vertically the height of the house. There are two hubs in the basement and I would like to remove the cast all the way down to the first hub, and replace it with PVC all the way up to the roof. I talked to the local building inspector, and he said that 3" waste pipe is fine since there is only a tub, a sink and a toilet draining into it, and not all at the same spot, but that when I get into the attic, I will have to bring the size back up to 4" to come out of the roof, as it's code to have 4" out to the roof, but only 3" in the house.

Just need to find the best way to get the pipe pushed back further, so it recesses in between the two wall studs, and not out into the room.

I am thinking of using two 45 bends to get it back the distance I need it to, or perhaps using a T to bring the pipe back to where I need it to. Two 90's don't have enough clearance.

in the basement.

can you give me a picture of the pipeing configuration as it goes thru the floor?

I can, but I cannot do it until I leave work today.

It's a really basic setup. There's cast iron all the way down to the floor, which has a Y and a cleanout on it. From there it goes straight up into the kitchen and up even further into the bathroom and then roof.

if the waste stack is picking up just that bathroom. there is no reason it can not be 3''

cut the pipe in the basement, use a 4'' castiron x 3'' pvc reducing mission band

offset the 5'' you need using 2- 22.5 degree fittings. before going thru the floor to the kitchen

and you will never have a problem

That would get it offset in the basement, but how do I get it offset at the top? Or was using those two elbows what you were referring to at the top?

offset in the basement go straight up. cover it up up stairs..need pictures

what is that? back up, to close

I had my friend come over this weekend and run the new line, and he was able to get it moved back into the wall where I need it to be. I am not sure what you are referring to as far as a 'dead spider', but there were spider webs all over it. Didn't see any spiders. There was also the skeletal remains of a bird that must have flown into the stack a long time ago.

Thanks for the information!

glad you got it moved..

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