Can Sealing a Washer Drain Cause Pressure Issues in a Multi-Story Building?

[gjonesy]

We recently had a flooding issue with our building I live in the basement apartment, The building is 3 stories, the ceilings are approximately 10-12 feet interior 4inches subfloor ( concrete/steel ) 26-28 feet of vertical fall on a 2 inch washing machine drain to the bottom apartment. I am sure the kitchen drain is tied into this drain but the one of the ladies in the office suggested the drain was tied into the tub and showers also. (This would not be to code for a newer building I believe, I live in NC) this building was built in the 70's. Water from time to time comes out of the washing machine drain when we are washing clothes. I know water flows the path of least resistance and I was wondering if I could (rig it) with a sealed cap, so water can not go passed the opened end of the washer drain. I know the drain itself is to small to support that volume of water. Since we live in a 3 story building our apartment is the lowest point. I have found screws and angle stop handles in our toilet coming up from the line because of the pressure of falling water.

My only concerns are would this then cause so much pressure it would:
A. start coming out of the kitchen sink?
B. damage the line in another area?
C. Work and solve the problem?

Not sure how the system is vented but, we normally do not have "Flooding problems."

Thanks

addendum: when I say (normally we don't have flooding problem) It means it's happened multiple times but not every time. Kind of an occasional problem.

 

[gjonesy]

I should also say that this issue is time sensitive considering we discovered that the box containing the drain has rusted out an when it overflows it leaks into the wall floods the kitchen also now.

 

[OldYat47]

The problem is "downstream". The drains and sewers should have been designed with adequate safety factor that this should never happen, even if everyone is draining water at the same time. Contact the supervisor/maintenance man and report the problem. A plumber should be able to either snake or camera the drain lines to clear or see any obstructions (so-called "flushable" wipes, hardened cooking grease, sanitary products, etc., etc.). If it's bad design then installing check valves is a good solution, though far from ideal. Stopping backflow at the washer could, indeed, cause problems at the sink.

 

[gjonesy]

Stopping backflow at the washer could, indeed, cause problems at the sink.

That's what I was thinking, I also think its a design flaw, its a 2" line with 3 double sink basins 3 washing machines, and possibly 3 tub and showers connected. since the toilet doesn't seem to be backing up and (if its to code) should be the last on the 4" line to drop in. It has to be backing up in the 2" correct? I did some mechanical contracting and welding (also limited plumbing) I know how plumbing is "supposed to work" the fact that we keep finding objects in the toilet presumably from back pressure leads me to believe there has got to be a venting problem also. Just to be clear the toilet is not backing up and over flowing, just every now and then we find "odd objects" (Handles screws rubber washers) in the toilet.

Contact the supervisor/maintenance man and report the problem.

We did, and all they did was send a crew with fans and a industrial dehumidifier...they dried up the floor, also messed up a wood working project (it dried some of my wood to the point of cracking). Other then that they aren't really trying to do anything that I can see. I was going to simply place a 2" rubber endcap with a pipe clamp , cut a hole in the center and glue the washer drain in it.

BUT I think one of 2 things will happen, it will back up in the sink number 1. OR blow the cap off and flood the bathroom again.

If it backs up in the sink at least we won't have water to clean up. A check valve is a great idea BUT the apartment is built on a concrete slab. something tells me the complex won't foot the bill for that.