This is likely the one pipe I would never compromise with. The sudsing effect and simultaneous use by other units could make for an interesting event on the first floor unt...
We have actually oversized them in the multi-family projects I used to do and still have had issues...
Anyway...just keep an eye on it over the short haul. If you get thru the first several months, you are likely good to go...
Like AtBC, I buy and sell as-is, where-is, subject only to survey and clear title. If the buyer has an issue...on to the next...
It's not connected to any other units. It's a vent pipe that goes to the sewer. No one else uses it. There's only one other unit above me and they have a separate laundry room. It should be handle the flow from a small washing machine.
If worse comes to worse, I'll just jackhammer up the concrete about a foot and a half down, cut the pipe out and put in a much wider one. But given how much water I pushed through it the other day to test it, I don't see it being a problem. Not to code, but some how I don't think buyers will mind when they look at an open kitchen.
