Wash machine stand pipe drain size requirement

[AJay]

Wash machine in 54 year old house currently drains into deep sink. Would like to add stand pipe in wall instead as we renovate laundry room. Was going to do this similar to the attached image. However I am not sure if the drain that goes down into the floor, which at point is a slab and not accessible in the basement, is a 2" pipe. So converting that to a 2" is not possible. Most existing drains and vents are copper with cast iron stacks. Other side of the wall is the garage so accessing piping is easy enough. Replaced the drywall on that side and didn't mud it up so will be opening that up today to check.

And if we do have 2", we intend to also keep a sink in the room. Does that drain rough-in height have to be 16".

Thanks very much.

 

[AJay]

Just checked and the drain is only 1.5” that goes down into the concrete

 

[skeezix]

My 2-cents' worth:

I don't like standpipes for washing machine drains. A clog somewhere between the washer drain hose and the sewer pipe that prevents draining means water all over the floor. Living in a house with a finished basement I don't care to deal with the mess. I've ALWAYS drained my washing machine into a laundry tub.

 

[Twowaxhack]

Pipe it all with 1.5”

 

[arctic bill]

Wash machine in 54 year old house currently drains into deep sink. Would like to add stand pipe in wall instead as we renovate laundry room. Was going to do this similar to the attached image. However I am not sure if the drain that goes down into the floor, which at point is a slab and not accessible in the basement, is a 2" pipe. So converting that to a 2" is not possible. Most existing drains and vents are copper with cast iron stacks. Other side of the wall is the garage so accessing piping is easy enough. Replaced the drywall on that side and didn't mud it up so will be opening that up today to check.

And if we do have 2", we intend to also keep a sink in the room. Does that drain rough-in height have to be 16".

Thanks very much.


View attachment 29773

I do not like this at all, the p trap on the stand pipe should be as low as possible , also the pipe between the ptrap and the connection for the washing machine should be 30 inches long