Moving toilet and sink in my 1928 house

[richdizz]

I am remodeling a bathroom in my 1928 tudor home built ona pier and beam foundation. The original bath layout was not thoroughly designed...the bathroom door opens into the toilet and the shower door opens into a large pedestal sink. Since the bathroom is torn apart for the remodel, I thought I would improve the layout. As such, I have several questions on waste/vent plumbing for the proposed configuration. Specifically around moving the toilet drain location 5-6 feet from the existing position. First a few diagrams/images for illustration:

Figure 1: Original and Proposed Layouts


Figure 2: Exposed Wall with Notes


Figure 3: Crawlspace Plumbing Reference



Plan/Questions
My plan is to cut the cast iron arm (D in figure 3) and attach a pvc sanitary elbow (via mission coupler) to run a new 5-6 foot pvc drain line to the new proposed toilet drain location. I would like to splice the sink into this same drain line. My questions are:

1) Do I need to run a new vent for the toilet? Most reading I have come across states that additional venting is needed with the critical distance exceed 6 feet (see example in figure 4). However, I had a plumber tell me this weekend that plumbers (at least in Texas) are adopting/following a new international standard for critical distances and that I could get away with 10 feet. Does this sound right?

Figure 4: Typical Critical Distance Diagram


2) If I do need a new vent for the toilet, can I create an auxiliary vent off the new drain line such as depicted in figure 4?

3) Can the sink splice into the same drain line the toilet will use as long as that splice extends upwards in no less than 45 degrees from the drain line?

[Terry]

I like picture #4

Everything is vented.
We like to see a combo for the vent if it's on it's back and within six feet.
The way it is shown does all of that.

If the lav is near the toilet, and you have 2" venting, then you can throw in a 2"x1-1/2" santee on the vertical and it would be wet vented over the toilet. That would be one way to have the lav closer.

[richdizz]

So something like this where the lav is attached to the toilet vent making it a wet vent? Also, how would I join the new pvc vent into the existing cast iron vent (A in figure 2 above).



Thanks!

[hj]

I would check into a Neo-angle shower to eliminate the door facing directly into the toilet. There are many ways to do the piping and what we would suggest after looking at the pictures might be vastly different than how we would do it once we actually saw the site.