View Full Version : Replacing Cast Drain Project

10-04-2009, 07:59 AM
Related to this thread where I outlined the problem of having a sewer smell coming into our house via the perimeter drain in our basement catching ground water (http://www.terrylove.com/forums/showthread.php?t=28038&highlight=sewer+smell):

Getting ready to replace the cast iron lines from the house to the septic tank, and when we do so, we are going to do a bit of drain line replacement inside the house as well. Here is what I've currently got going on.


We plan on cutting out all the cast and replacing with PVC except for the vent stack that runs through the roof.

I've read a bit about making sure the vent stack is supported when you cut the rest of the supporting drain lines away below it. What is the best way to do that? We'd be cutting it right where the word "vent" is on the photo.

Second question is related to how the vanity sink drain is connected to all this. As you can see, it currently runs vertically into the basement very near the main drain stack, but instead of connecting in the most direct way, it then runs horizontally away from the main drain stack and does this:


Any reason why I can't connect it more directly when I redo everything? Or is there a venting related reason this was done this way?

10-04-2009, 09:50 AM
Wow, look at the lack of support on those potable lines, and those 1/2" branch lines are putting stress on the tees...no wonder people complain of pex fittings snapping!

You would have to support the stack from the floor above before you cut it.

The vanity drain should be draining directly into the main stack.

10-05-2009, 07:40 AM
Found a few discussions on this board and others related to using riser clamps, so to be extra safe, my plan will be to install one up in the attic spanning the joists up there and another as close to the basement ceiling as possible supported by either vertical 2x4s that sit on the basement floor OR by short horizontal 2x4s nailed into the joists. Sounds like that should do it...

The long term plan for the other side of that wall that is framed is to finish that space, so having that vanity drain run into the main stack directly will clean things up a bit...I just wanted to make sure there wasn't a reason it was run away from the stack in the first place.

I'll continue to post photos and lessons learned as I go - this forum has been a great source of information and assistance!

Ian Gills
10-05-2009, 07:55 AM
I just supported by gas pipe at the weekend. It is fifty feet long and was being supported by just three one inch wire hangers. The mind boggles.

I have now supported it every sixteen inches.

10-05-2009, 09:00 AM
Well, I won't be able to support it that frequently because I don't want to tear into the 1st floor wall that it runs through, but I'll be supporting it as much as possible...

I am guessing that there is a horizontal connection to this vertical vent stack located in that wall that runs from the vanity sink to vent it, so if that is the case there is "some" support, but not enough to make comfortable whacking into it without doing anything else. :)

10-06-2009, 05:57 AM
What kind of gas pipe needs to be supported every 16"? Every 10' or so is usually MORE than adequate.

10-19-2009, 05:07 PM
So I'm wondering if there is a better way to hook my washing machine drain into the system when I re do these drain lines.

In the 1st picture in my original post, you can see the clean out for the main drain line that runs horizontally through the wall. The top of this main drain line is 51" above the floor.

Currently the washing machine emptys into a "temporary" stand pipe (a 2" diameter section of PVC) that runs directly into a sump pit. The sump pump then pumps the water up to nearly ceiling level where it connects into the vertical portion of my main drain line, where gravity then allows it to flow down and out of the house.

Is there a way I could plumb the standpipe, p trap and a horizontal run so it would run straight into the main drain line? So essentially all that would need to remain above 51" and would allow me to eliminate the sump pump...

From the top of the horizontal drain pipe to the bottom of the floor joists above is 35".

I can redo it the way it is currently if I have to, but obviously it would be great to eliminate that pump if I can...

Peter Griffin
10-19-2009, 07:03 PM
What up wit dat san tee lying on its side?

10-20-2009, 04:28 AM
Peter - are you talking about where the sink drain meets the tub drain and they connect? I asked above in this post about whether or not there was a reason it was originally run that way and someone else said "no." So the sink drain will be routed directly into the vertical stack when I redo everything.

I'll admit I did put it there when I had to do an emergency cut out of the long run of galvanized that made up the sink/tub drains, but in my defense I was just replicating the way it had been done before me. :o

10-20-2009, 03:00 PM
supported by either vertical 2x4s that sit on the basement floor OR by short horizontal 2x4s nailed into the joists.

Use lag bolts if you put the short 2x4's on the bottom side of the joists. Nails could just pull out w/ the weight.

Actually...nailing into the side of the joist into the end of the 2x4 might not be much better. That's a lot of weight on the nails and half of the thickness worth of end grain. .. best to built a little shelf for the 2x....