Plumbing in the Home/Trap in standpipe


Hi Jay,
I just bought a house from a DIY builder that did not put a trap in the standpipe next to the washing machine.  It is in a finished wall.  If I cut into the wall and cut the stand pipe somewhere above finished floor, can you think of a configuration that would allow me to exit the standpipe, put in a p-trap and then return to the standpipe?  Perhaps I could go to the next stud bay over, put the p-trap and then return to the previously cut standpipe?  One other way to describe what I am trying to do is to insert a p-trap into a standpipe without moving the washer box and without changing the location of where it penetrates the floor.  The standpipe is 2" diameter and the top of the standpipe is about 34" above the finished floor.  Perhaps I can cut the standpipe at 18" from the top, elbow into a horizontal pipe that goes over to the next stud bay, then to a trap and then loops back under itself to return to the bottom half of the cut pipe.  Provided I do not run out of vertical space, is there anything wrong with doing this?

Thank you,

Other than cutting the line below the floor in the basement, and trapping it down there, the only other recourse would be to move the laundry box to an other location in the room or to cut open the stud space and pipe it over and back to the original line. If you choose this  way, be sure to leave as much pipe as possible between the point where the machine hose is inserted and the first elbow you install in the line. The reason is that you will want to stop any splash back that may occur when the machine pump starts.

Plumbing in the Home

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Jay Nicholas


Plumbing & Heating (warm air, hot water & steam heat)


40 years in the business, 40 years as a lic. master plumber in NY State. Retired

Graduated Magna cum laude at the School of Hard Knocks

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Commercial, residential and light industrial. You name it ...I have probably worked on it

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