branch height

[craignlisa]

I am installing a washing machine in the basement of a 4-plex. I do not want to break the concrete floor to access the drain. This will be done in a year when the client decides to build a bathroom here. The 4" cast iron main drain/vent that comes from upstairs has a branch for 1-1/2" tubing off of it. It is located 2 to 2-1/2' from the floor. I've already cut off the old 1-1/2" galvanized pipe and replaced it with abs tubing joining them with a rubber coupling (Fernco). This tubing comes from the renovation I did upstairs in the apartment. The washer/dryer from upstairs is to be located in the basement. Can I simply install a "Y" in the branch I mentioned or is it too high. I have heard that the washer pump will overflow the pipe because the branch is too high from the ground. Keep in mind this is a temporary fix (1 year max.).

Craig

[LazyPup]

There are a number of code issues to be considered here.

First of all, a washing machine standpipe requires a 2" diameter trap, and the line may not be smaller than the trap. The alternative would be to install a Laundry Tub, which may discharge into an 1-1/2" line, then discharge the washing machine into the tub.

The next concern is the load on the existing 1-1/2" line. A horizontal 1-1/2" line is rated for a maximum load of 3DFU's (Drainage Fixture units). There is no mention of what is already discharging into that line, but a Washing Machine or laundry tub would add another 2 DFU's, therefore the maximum existing load on that line could not exceed one bathroom lavatory (1DFU).

This whole configuration would also fall into a rather gray area of the code, and would require the approval of your inspector. Technically speaking, since there is a toilet attached to the stack on an upper floor, the portion of the stack from the toilet waste arm connection down to the house main is classified as a "WASTE STACK".

Sink drains may not be connected to a "Wet Stack" downstream of a toilet however a waste stack may receive a branched drain, providing the branched drain has a separte auxillary vent.

[craignlisa]

The "branch" I'm referring to is in the vertical 4" drain pipe. The old configuration had the apartment of my client drain into the same 2" pipe the apartment of the tenant above her drained into. This 2" pipe then was branched to the main 4" waste stack just below the floor of my client. When in the basement this joint is of course at ceiling level. Now since the washer/dryer is being re-located in the basement, the tenant upstairs is the only one using this drain pipe. So the load on the 4" stack is now under-used.

As for the 1-1/2" pipe I mentioned, the only other tap to it is the bathroom sink from upstairs. It comes thru the floor and joins at the 2' to 2-1/2' branch that I mentioned in the 1 posting.

Craig