Adding bathroom to basement

My basement has no bathroom and now that I have added a home theatre it is much more inconvenient to run upstairs in the middle of the film (and for some reason it always happens at a highly dramatic moment).

So I was thinking about adding a bathroom. I've worked out a layout and here's where I'm stuck.

Joining the main stack for a toilet. Presumably I have to dig a channel, lay the ABS waste pipe at a slope, tie into the main stack and then make good the concrete floor. I think I have two stacks - the one I want to use (i.e. the nearest) services a bathroom upstairs (so toilet, bath and basin all vent and drain through this stack). Is there any problem adding to this? How do I tie into it - the connections from above are a bit of a mess and I'm worried about what the pipe will look like underground - could it be metal?

To dig my channel I presume I will need to use a concrete saw to cut the outline and then jackhammer the channel. I've never done this - any tips? Anything I need to know about when making good the concrete afterwards e.g. dpm, rebar?

There is an odd floor drain in the area for the new bathroom - I've never seen or heard water flow in this drain and when I have poured water down it it drains fine but I don't know what it drains into - not my sump. Any ideas on where this would drain or how I can find out?

The stack vents through the roof and as far as I can see all the drains for the upstairs bathroom use this one vent. Can I do the same? The drain run from the basin will be about 6 feet to the stack - is this too far for venting?

bathroom

quote; I've never done this - any tips? Anything I need to know about when making good the concrete afterwards e.g. dpm, rebar?

The best tip we can give you is related to your first five words in the above quote. You have NEVER done this before and NOW is not a good time to start, unless you first take a course in Plumbing 201, (Plumbing 101 just deals with minor repairs). Fail to do this and you will create a system that will hound you for the rest of its life. The first step is to take your drawing down to the city building department and have it approved then get a building permit for it.

hj said:

The first step is to take your drawing down to the city building department and have it approved then get a building permit for it.

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Well someone got out the wrong side of their bed today!

Just out of curiousity - have you ever done a plumbing job where you didn't apply for a permit when strictly you should have done? I've called 3 plumbers and a general contractor about this job - each one said that a permit was required but they were prepared to do the job without one.

In any case, I have applied for and received building permits in the past - I don't think I need any advice on this.

permits

You have no idea how to install the plumbing system, based on your question, so if you are going to do it yourself a permit and inspection is the ONLY way to ensure that it is being done correctly. A profressional will do it the way the code requires, so if the owner wants to risk doing it without a permit and inspection, at least it is correct. I get up on the same side of the bed every day, but do not wish to give a complete course in plumbing sewer, drain, and venting over the Internet on any day.

hj said:

You have no idea how to install the plumbing system, based on your question, so if you are going to do it yourself a permit and inspection is the ONLY way to ensure that it is being done correctly. A profressional will do it the way the code requires, so if the owner wants to risk doing it without a permit and inspection, at least it is correct. I get up on the same side of the bed every day, but do not wish to give a complete course in plumbing sewer, drain, and venting over the Internet on any day.

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Of course I have an idea on how to install the plumbing system - sheesh, just because you know (a lot) more than me doesn't mean I have no idea! My ideas are not perfect, indeed some are probably completely wrong - that's why I have asked for advice.

I don't want to get into an argument - I am grateful for your input even if it has not been of any use. It is not my experience nor does anecdotal evidence support the faith you place in permits, inspections and professionals. None of these will "ensure" the task is done correctly and nor does it necessarily mean that because I haven't done a complete course in plumbing I will do the task incorrectly.

How about just answering my questions, please? Here's my questions rephrased:
1. I guess that there is a capacity limit for the number and size of drain pipes entering a stack. I don't know what this is. At present there are a 4" toilet waste, 1.5" bath drain, 1.5" basin drain, 1.5" kitchen drain and 1.5" basement basin drain - I want to add a 4" toilet and 1.5" shower. The stack is 5". Is that within code?
2. Adding to the stack from below looks difficult because of all the pipes above some of which are metal (copper and iron I think). Is this as difficult as it looks, should I replace the metal? And are there any methods of joining to the stack to make this easier? The stack into the concrete is ABS but I don't know what happens below ground (yet).
3. I guess there is a code requirement on the distance to a vent. My basement bathroom will have the basin drain about 6 feet laterally from the 4" vent (and 10 feet or so below it). Is this ok? Would it be better to re-vent or do I need a new vent?
4. Does anyone have any tips on cutting the concrete for the waste pipe? This is not a post-tensioned slab. And any tips on making good e.g. experience with liquid dpm, where and how to add rebar, etc?

how sure are you that the stack is 5"...

Cass said:

how sure are you that the stack is 5"...

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As sure as I can be! The exterior circumference is about 16" so it is definitely bigger than 4.5" and smaller than 5.5" ID. Most of the stack is 4" until it is about 2 feet from the floor where it is converted to 5".