Five stories is not enough to have to worry about relief vents, and I assume you will not have kitchen units, or at least not a separate sink stack. If you do have kitchens on a separate stack, connect the one on the lowest level to the drain after the elbow at the base of the stack. Other than that, I cannot think of anything that would be unique to a five story building.: I am a plumber in clifornia, my company is getting ready to start a motel in the town that i live, the motel is going to be 5 stories and we were wondering about any special codes that would diviate from regular residential codes.