Let's assume that this building meets all requirements of 206.2.3 Exception 1 so no elevator is required in the building. Let's also assume that the seating area of the mezzanine dining area you mention contains more than 25% of the total combined seating area and focus on the more difficult question you seem to be asking.
The conversion of bank spaces in a pre-ADA building into a restaurant is clearly an alteration affecting the usability of primary function areas so normally the path of travel obligation would apply. However, Exception 2. (below) in 206.2.5 does not require an elevator to serve the mezzanine in an alteration serving a dining area that meets all of the criteria in the exception:
“206.2.5 Exception 2. In alterations, an accessible route shall not be required to existing raised or sunken dining areas, or to all parts of existing outdoor dining areas where the same services and decor are provided in an accessible space usable by the public and not restricted to use by people with disabilities.”
However, this building already has an elevator serving the mezzanine level but the owner wants to close it to the restaurant users. The requirement in 203.2.1 says "An alteration that decreases or has the effect of decreasing the accessibility of a building or facility below the requirements for new construction at the time of the alteration is prohibited." Since this requirement prohibits a reduction in access (closing the elevator to restaurant users) below the requirements for new construction, but doesn't mention how to reconcile that with the alteration exception, which one trumps the other? Very good question.
You have to go back to 206.2.5 and Exception 1. That says:
“206.2.5 Restaurants and Cafeterias.
“In restaurants and cafeterias, an accessible route shall be provided to all dining areas, including raised or sunken dining areas, and outdoor dining areas.
“EXCEPTIONS: 1. In buildings or facilities not required to provide an accessible route between stories, an accessible route shall not be required to a mezzanine dining area where the mezzanine contains less than 25 percent of the total combined area for seating and dining and where the same decor and services are provided in the accessible area.”
The two keys to the answer are that no elevator would be required in the building in new construction because no floor in the building has more than 3000 square feet of floor area, but no mezzanine dining area can be constructed on an inaccessible mezzanine that exceeds 25% of the total combined area for seating and dining because that wouldn’t even be allowed in a new non-elevator building.
If I were the new restaurant owner or landlord, wanted more seating on the mezzanine, and really concerned about security, I would install a security device on the elevator control panel to fix that problem. Then I wouldn’t have to worry about it again.
