I'm assuming that memory beds would be considered long term care, in which case it sounds like a mixed-use property and you'll need to determine the primary purpose. I'm guessing there will be parts of the facility for staff and other non-residential purposes, so it might not just be 58 v. 25. You can use any reasonable standard.
5. Properties with service and medical components. For purposes of § 1003.2(f), a property used for both long-term housing and to provide related services, such as assisted living for senior citizens or supportive housing for persons with disabilities, is a dwelling and does not have a non-residential purpose merely because the property is used for both housing and to provide services. However, transitory residences that are used to provide such services are not dwellings. See comment 2(f)-3. Properties that are used to provide medical care, such as skilled nursing, rehabilitation, or long-term medical care, also are not dwellings. See comment 2(f)-3. If a property that is used for both long-term housing and to provide related services also is used to provide medical care, the property is a dwelling if its primary use is residential. An institution may use any reasonable standard to determine the property's primary use, such as by square footage, income generated, or number of beds or units allocated for each use. An institution may select the standard to apply on a case-by-case basis.