I saw a response in another thread re: Removal of Cast-Iron Vent Stack. The question was why remove a perfectly good vent stack and replace it with inferior materials? That question resonated with me.

I purchased the house last year and soon afterwards found problems with this bathroom. I ended up tearing it out, down to the studs and floor joists. The problem is that I have a cast iron sanitary tee that is not low enough to allow for enough fall for the drains in this bathroom.

After I tore out the bathroom, this is what I found.

http://www.flickr.com/photos/103054897@N08/9904748156/in/photostream

Notice that the double joist near the far wall has been cut completely in two. There's a metal bar extending from the basement wall at the top of the photo to the second floor joist (Shiny bar next to the copper pipe).

http://www.flickr.com/photos/103054897@N08/9904748156/in/photostream

That joist, which was notched halfway through, ties into a header that is supported by two pieces of plywood. The notch was for the drain from the bathtub. The next two joists were also notched... overall a very bad job. The header was chopped up and the two pieces of plywood are shown here.

http://www.flickr.com/photos/103054897@N08/9904748156/in/photostream

The toilet leaked and the nails and screws were rusted. It was a disaster waiting to happen.

The vent stack/drain is 4" cast iron pipe by Clay and Bailey. It was poured into the concrete basement wall. There�s a clean out near the basement floor. The pipe extends up through the concrete wall to a sanitary tee that was poured into the wall and connects to a drain line from another bathroom. That drain line comes from the crawl space beyond the concrete basement wall. I have broken out the concrete around the lower sanitary tee so that the lower sanitary tee is fully exposed.

http://www.flickr.com/photos/103054897@N08/9904748156/in/photostream

The upper sanitary tee is connected directly to the lower tee and is shown in the first photo above.

I have removed all of the floor joists and built a wall in the basement to support the new bathroom floor. The new joists will be double 2x6s running perpendicular to the old joists.

So, here's the problem. There's not enough fall for the new shower or sink drain to the upper sanitary tee. I was planning to remove the lower sanitary tee, the upper sanitary tee, and everything above them to the roof. Then replace the lower sanitary tee with a PVC double sanitary tee to drain both toilets... the one in the guest bathroom and the one in the bathroom I'm replacing. From there, I go up through the roof with a PVC vent pipe.

The cast iron is in good shape all the way. The only problem is that the upper sanitary tee is not low enough. Got any better ideas?