Length of P-trap drain stub-out from the wall

[Dohc]

Trying to finish a rough-in for a new DWV kitchen and bathroom and want to know how to rough in the stub-out from the wall? Without the cabinet and sink installed yet, it would be hard to determine the exact length of the short horizontal piece that goes from the trap into the wall. What do the professionals do in this case? If I make it extra long, glue it in, and then cap it with a cover for DWV testing, do I just try and cut it back after the cabinet is installed? When I do cut all my PVC I always try and use a miter saw so I have a perfect square cut, and I hate cutting installed PVC as it never turns square for me.

Note: stub-outs show for reference, not glued in yet, as I don't know how long to make them.

 

[Terry]

I install long and cut back when setting fixtures. That's how most of us do it. Nothing worse than having to add a coupling in a bad spot.

 

[Sponsor]

 

[Jeff H Young]

Trying to finish a rough-in for a new DWV kitchen and bathroom and want to know how to rough in the stub-out from the wall? Without the cabinet and sink installed yet, it would be hard to determine the exact length of the short horizontal piece that goes from the trap into the wall. What do the professionals do in this case? If I make it extra long, glue it in, and then cap it with a cover for DWV testing, do I just try and cut it back after the cabinet is installed? When I do cut all my PVC I always try and use a miter saw so I have a perfect square cut, and I hate cutting installed PVC as it never turns square for me.

Note: stub-outs show for reference, not glued in yet, as I don't know how long to make them.

Looks good I can tell you care about the job. As Terry said we just glue apiece in thats long enough , too much going on to guess at proper length . Sometimes on a small job Ill know exactly where the end can be and put it in just right. I dont like having a coupling under the sink but.... the one thing worse than glueing a coupling on is getting my fat self under the cabinet to cut the pipe HA HA some are very tight. So if instead of cutting the pipe it needs a 22.5, 45 or coupling first thing no biggie. If I know its a real tight vanity like one with drawers on one side Ill definately not put a long arm on it.

 

[wwhitney]

I hate cutting installed PVC as it never turns square for me.

Try this: take a piece of paper (or some blue tape sticky side out, or whatever) and wrap it around the pipe 1.3 times (+/-). If it has a straight edge and the edges perfectly align in the overlap, the edge should be square to the pipe around the whole circumference. Slide your sleeve to your cut mark and tape it in place to use as a cut guide.

Cheers, Wayne

 

[Jeff H Young]

If I had nickle for everytime a plumber put a wrap around to cut a dirty arm square under a sink, Id have zero sence I mean zero cents. and then check it with a square and take a rasp to it come on overkill!

 

[Reach4]

Idea: put a long pipe in place but not too tight, and not glued. Then, after the wall is done, glue trap adapter to a pipe, and cut the other end to the right length-- compensating for socket depth. Apply primer with a long dauber lashed up for the purpose, prime the pipe and apply glue. Insert, and twist.

This is not suggested for somebody who is not a little OCD, or at least a slow perfectionist.

 

[wwhitney]

If I had nickle for everytime a plumber put a wrap around to cut a dirty arm square under a sink, Id have zero sence I mean zero cents. and then check it with a square and take a rasp to it come on overkill!

Different strokes for different folks.

A professional will likely know what level of precision is good enough and have the experience to make the cut freehand. Some DIYers prefer to err on the side of greater precision, and may not have as much experience making the cut.

Cheers, Wayne

 

[Jeff H Young]

Different strokes for different folks.

A professional will likely know what level of precision is good enough and have the experience to make the cut freehand. Some DIYers prefer to err on the side of greater precision, and may not have as much experience making the cut.

Cheers, Wayne

poking a little fun. a nice cut is allways good ! the paper wrap arround is a good trick use it all the time fitting up weld pipe

 

[Dohc]

Idea: put a long pipe in place but not too tight, and not glued. Then, after the wall is done, glue trap adapter to a pipe, and cut the other end to the right length-- compensating for socket depth. Apply primer with a long dauber lashed up for the purpose, prime the pipe and apply glue. Insert, and twist.

This is not suggested for somebody who is not a little OCD, or at least a slow perfectionist.

Reach4, if the pipe is not glued in, I can't use the rubber furnco cap, and then we wouldn't be able to test the system. I assume there is a better/similar way to plug the hub/socket then instead of the Furnco?

 

[Reach4]

Reach4, if the pipe is not glued in, I can't use the rubber furnco cap, and then we wouldn't be able to test the system. I assume there is a better/similar way to plug the hub/socket then instead of the Furnco?

I had not considered testing. Sorry.