Does anybody know of any code requirement or rule of thumb for the length of the vertical pipe above the trap that a washing machine drains into? We have one that extends only about a foot above the water level in the trap, and sometimes some foam comes out the top.
Thanks —
— J.S.
Use these assembly techniques when installing crown risers and molding to minimize visible gaps and nail holes.
Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.
Start Free Trial NowGet instant access to the latest developments in green building, research, and reports from the field.
Start Free Trial Now
Replies
IRC allows 18-42" standpipe, UPC allows a 30" standpipe.
Dunno about code, but the ones I've seen run roughly 18-24". Generally the machine itself will be speced to lift to a height (upper elbow) of 6 feet or so, and can in most cases go 8-9 feet high without problems, so extending the standpipe another 6-12 inches shouldn't be a problem if there's clearance for it.
Overflowing from the standpipe, however, is often a sign of a partly clogged pipe. Not necessarily the trap, but in the horizontal runs under the floor. Laundry lint/soap generates a rather tenacious scum that sticks to pipes like glue and builds up anywhere where the slope of the pipe is a hair shallow. Occasional (every 5 years or so) cleanouts with a power auger may be needed.
I installed one at 18" above the trap as per instructions on the package. When the plumbing inspector was over he advised me to lower the trap as far as possible. This making the standpipe longer. Even though I was okay according to code ,he said washing machines today pump harder than years ago and better be safe than sorry. I did as he said, no problems.If it is possible, just cut the pipe, lower the trap and install a longer standpipe.
mike
Columbus now has a code that for horizontal runs for the washing machine drain they need to be 3" pipe. Don't know if this is widespread or not.Sure caused a problem in my design.