Ok. I ended up calling the local AHJ and I can classify the enclosure as I-2, the same as the hospital. While our client did say that it does not need to be sprinkled the AHJ says it does. Outside of that I do not need to have a fire rated wall assembly around the exterior of the enclosure. It will be considered an incidental use building which would either require and automatic sprinkler system throughout just the same as the existing hospital does or will need 1 hour fire rated walls. Local AHJ wants a sprinkler system.