When you’re working out occupancies on existing buildings, keep in mind that any change in occupancy is considered an Alteration (Section 202 Definitions). That means that even if your client is just doing cosmetic work that wouldn’t normally be an Alteration (such as normal maintenance, reroofing, painting, or mechanical and electrical system changes), the change in occupancy alone classifies it as an Alteration.
The priorities of the Path of Travel upgrades are primary entrance, toilet and bathing facilities, drinking fountains, public telephones, and signs. See Section 11B-202.4 for more information, including many listed exceptions.
More and more cities require drawings documenting the existing non-conforming conditions, in addition to the new proposed work. This gives them a reference document for future remodels, and allows the plan checker to have all the information needed for negotiating with you which pieces should be upgraded, which might include elements that were in compliance when built, but that don’t meet the current code.
So the bottom line is that if a client comes to you just wanting help with a change of occupancy, do your research, talk to the building official about what accessibility upgrades they might reasonably require before your client just gets a Zoning approval for a change of occupancy and starts moving in.