As you can see from this picture, rental unit 6 (room 91) used to be connected with the main household. The unit is symmetric with rental unit 5 which has neither evidence for stairs nor for connection to the main house. Unit 6, however, was clearly blocked off at some point in the development of the insula, and perhaps stairs were added to a second floor pergula later when the rental business started expanding and demand dictated another taberna cum pergula! The blocking off in this case, just as in room 92 (unit 7), must have been relatively early, since there is a significant difference in floor levels between the atrium and the rental properties. You might be able to tell from the picture that the atrium floor reaches high up on this filled doorway.