I am plumbing under a new house (crawl space foundation). My question concerns the drain. There is a 4' pvc sleeve going through the footing. I was planning on using 3' pvc for the drain. Should I run the 3' pvc through the 4' sleeve or us an adapter to increase to 4'?

Is the four inch pipe poured directly in the concrete? If so, I would run three inch through it, not adapt to it as it may crack in the future due to settling. Now, another important question is how many fixtures are in the house and what kinds. Please list all toilets, sinks, washers, etc. In my area we are allowed to run three inch for the main, but we always run four inch min. If your area allows three inch, and your total fixture units is within range, then I would stub three inch through the for inch(like I said if the four inch is poured directly in the concrete) then increase to four inch directly outside the home.

One more thing. Are you sure its just a sleeve through the concrete, or is it the actuall drain already hooked into the city main or septic tank? And what is the thickness of the pipe through the concrete? Either way, you will want to run sch40 pvc through the concrete, then you can adapt over to thin wall sdr sewer pipe. Also, make sure to add a double cleanout just outside the home, and it never hurts to add one just before exiting the foundation.