So I am having problems with the drain line in my house. I'll give you the whole story so you can draw a full conclusion

1976 - House Built

August 2005 - I buy house.  7 days after we move in, the floor drain in the basement runs over.  We call a plumber who augers and finds tree roots about 53 feet out from the cleanout.  We rip up carpet and replace with tile.  

Winter 2006 - Backup again, but not as bad as the first.  Call a plumber who charges WAY too much, but finds roots again at 50+ feet..

2007 - Backup again.  I rent a drain auger an do it myself.  Find roots once again.  Start to treat with copper sulfate, but fall off doing this after 2 years or so.

January 19, 2014 - Wife tells me drain is backed up again.  I rent a large industrial drain machine and clean it out.  I find roots and spend lots of time running the drain machine after water drains just to be sure I got everything.  I end up with 2 big wads of fine roots, but on the third pass the auger comes back clean.

January 22, 2014  - I am out of town on travel and wife calls to tell me the floor drain backs up some when the washing machine runs.  The floor immediately around the drain was a little damp, but nothing worse than that.

Today - The wife tells me the washing machine backs up again. The washing machine drains directly into the floor drain. I pull the floor drain and it is full to within about 4" of the top.  If I fill the washing machine and let it drain.  It takes almost no time for the floor drain to fill up.  When I stop the washing machine the floor drain water level drains down quickly to 4" below the top and then stops.  I get out a 100' flat sewer tape I have.  I ran most of it in the drain until I hit a hard stop.  I estimate 65-70' of snake down the drain.  I figure this is where my lateral hits the city main.  I notice I can drain a full bathtub of water and the level in the floor drain only comes up 1-2".  There is a slight swirl in the floor drain while I do this, but very minor.  I tried to run a smaller snake down the floor drain, but I cannot get very far before I hit a hard stop.  I don't know if I am hitting a trap or something else.

Anyhow, here is my layout:


I am thinking there is something blocking the line between the floor drain and main line.  The upstairs drains fine and only the floor drain seems to be a problem..  The issue is I cannot get any kind of snake or auger down the floor drain.  What am I missing?  

Thanks to all in advance for the help!

Is it possible that it's a french drain?

Not sure I understand the question.  I know what a french drain is, but not sure how it applies here?

Is there a tree anywhere near where the main drain lies? Dimes to donuts there are tree roots in the main line.

My folks struggled for years with these problems and when Dad was out of town one week (he NEVER spent any money on anything he thought he could do) Mom got a Rotorooter out.

Never had the problem again.

There is a tree close the main where it ties into the city.  I'm sure this is the source of the roots.  In the past we have been able to keep this under control with chemicals.

What gets me is that the water level in the floor drain remains relatively constant.  When I drain a full bathtub full of water it rises 1-2" but comes right back down.  When the washing machine drains it tries to overflow if I dont stop it - but then it returns to the same level.  This really has me puzzled.

I'm going with not enough fall from floor drain to main line.  Also, it would make more sense to me to drain the washer into the main rather than the floor drain.

If you stick a plug in the floor drain,  will the washer drain fine?

What size cable in the machines you tried?  I'd go for 3/8" if that's a 2" floor drain.  Try a few different heads, it can be a pain jumping a trap but it's doable.

Also (if I'm seeing your potato cam pic right), the pipe coming up for the w/m probably doesn't have a trap underground since you have the discharge hose jammed in where the vent usually is and there's a cap where the trap usually goes.  You can try cabling from there if you can get it to turn away from the floor drain when it hits the horizontal.

Don't go too far with the 3/8" or you risk getting wrapped up in the 4".

Going to have to try again tomorrow.  I have a short auger that is either 1/4" or 5/16".  I'll try and hit the floor drain again tomorrow.  After seeing some pictures online, it looks like the trap could be real tight.  Might just take more patience and cussing.

So far as the washing machine drain, you are correct that there is not trap underground. In fact, the washing machine drain is tied into the floor drain just a few inches down from the finished floor. It comes right into the main chamber of the floor drain and I assume they are sharing a trap.  My best guess would be they did it this way so you would have a repeated flow through the floor drain trap and keep it full.  I've heard of lots of folks with problems with floor drain traps drying out and they have to add water regularly to keep the smell down.

This is more than likely what you're dealing with, but the wye for the w/m riser in this pic is probably a tee in your case.

In theory, the main stack and the building sewer should never be completely full of water.  As water is added to the sewer the air is displaced across the top of the water and up the vent stacks allowing the water to flow at a  rate that self scours the pipes.  Because your main is slow ( the roots?) the large volume of water that is drained from the tub causes back pressure on the floor drain's trap seal which causes the  water rise.  You likely don't notice the issue when using a hand sink because the sewer is able to handle that lower volume of water.  

Based on what you described, you need to replace the sewer.  If the laundry issue doesn't clear up after that you could cut in a new 2" drain in the soil stack to the right of the washing machine.

Got it fixed! I ran the big machine down the main line again. Somewhere between 70 and 80 foot I hit something. After a little work it is running again. There is still some work to be done (maybe video inspection) but for now we are flushing good. Thanks to all for reading and recommending.