Drain Lines,

Ok where to start? I call my house built by one of those weekend warrior type! I won’t even go into all that. I have about 20’ of 3” drain pipe on what looks to be about ¼” drop per foot. On that line I have two toilets, one vanity and one tub teed into it with another 3” pipe about 6’ long. (no vent) Then the other tub and vanity are on the main line. After that it transfers into a 1-1/2” line for about 30’. This slopes at first but then towards the other end it is just fasted up against the floor joist. In that line go the kitchen sink, dishwasher and wash machine. (no vent again) In the future I want to add a bathroom in the basement at the end of this 1-1/2” pipe. So my questions are this; 1) What is the proper slope for the drain line? I have always heard that it should be ¼” per foot. Is that correct? 2) Should I extend the 3” line the whole way to accommodate the basement bathroom that I want to add the future? This toilet, shower and vanity will need pumped up to the pipe. 3) What are the recommendations for venting the drain line? As of now every time I use the washer I get a wet floor in the basement. It never used to do this but it does now. I have snaked the line (the almost if not flat 1-1/2” line at places) several times from the wash machine.
Thanks,
Steve

1/8th to 1/4" per foot is good. Your drain pipe size is determined by fixture units. A little more than I want to get into right now. You should probably get a book on plumbing from the library or book store. Here are a couple of articles that will show you how your drains might actually be vented. http://www.plumbinglessons.com/sup/cloggeddrain.htm
http://www.plumbinglessons.com/sup/kitclog.htm

Hey Steve,
No vents huh? Every local, state and Universal code MANDATES that every fixture that has a trap MUST be vented. And that's just for openers.
1) What is the proper slope for the drain line? I have always heard that it should be ¼” per foot. Is that correct? Yes it is although if space is tight you may drop to 1/8th.
2) I want to add a bathroom in the basement at the end of this 1-1/2” pipe.
You can't do that.
3) Should I extend the 3” line the whole way to accommodate the basement bathroom that I want to add the future? This toilet, shower and vanity will need pumped up to the pipe.
Not if you're going to add a macerating system. While you will have to pipe and vent for the system since you will be using a macerating system increasing to 3" will not be necessary. To check out a system that will suite your needs click on; http://www.saniflo.com/ and read their installation instructions.
4) What are the recommendations for venting the drain line? A dedicated vent,( single vent out the roof, this vent can not tie back to a house vent.) will have to be run for the system in addition to a regular vent off the lavatory. The lavatory vent may be revented back into a dry vent if available.
Good luck and we are here if you have more questions. Tom