Cost to add a powder room

Depends on where the plumbing is . . . . is it easily accessible ?

I would guess 10-15K, are you sure your strict board will allow you to add a powder room? Most strict boards would not

Yes - there's already a washer dryer there. It's not $350k?

That is a very nyc way of thinking, if you really thought a powder room might cost mid 6 figures. I question the choice of forfeiting a laundry room for a powder room, but the laundry sows not necessarily mean you have an accessible waste pipe for the toilet. If you do, this is under $20 .

Have a plumber look at this first before you make any decisions