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2009,12,15 IBC 1108.2.9.1:
Where dining surfaces for the consumption of food or drink are provided, at least 5 percent, but not less than one, of the dining surfaces for the seating and standing spaces shall be accessible and be distributed throughout the facility and located on a level accessed by an accessible
2009 IBC commentary - Section 1108.2.9.1 establishes the criteria for the percentage of spaces at tables, booths, bars and counters that will be used for eating or drinking that must be accessible. This criteria is consistent with Section 1109.11 for the required percentage of accessible built-in surface in all other occupancies. The accessible
surfaces are also required to be distributed throughout the facility such that a comparable choice of locations and types ( i.e. tables, booths, counters, etc) is available see figure 1108.2.92.1) This requirement i, in conjunction with Section 1108.2.9. provides a reasonable and appropriate degree of accessibility throughout dining areas. The result is that a person with a mobility impairment will be able to approach, enter and move about in the dining area. In addition, 5 percent of the total spaces at dining surfaces provided must be accessible. Each seating location at a table or seat section of a bar is considered a dining surface. The issue of whether a portion of a bar or dining counter in a restaurant is required to be accessible is subjective. The assumption is that if other types of seating are provided adjacent to the counter, then services provided at the counter will also be available at the adjacent seating: therefore if adequate accessible seating is available adjacent to the bar area, the bar is not required to be lowered. IF the bar is the only eating or dining surface in a restaurant or in a separate room in the restaurant, then a portion of the bar must be made accessible.
The 2015 IBC Commentary says the following:
"...There are practical reasons not to require dispersement by type. If you require a high table to be lowered, you no longer have a high table...The issue of whether a portion of the bar or dining counter in a restaurant is required to be lowered is subjective. The assumption is that if other types of seating are provided adjacent to the counter, then services provided at the counter will also be available at the adjacent seating. Therefore, if adequate accessible seating is available adjacent to the bar area, the bar is not required to be lowered. If the bar is the only eating surface in a restaurant, or in a separate room, then a portion of the bar must be made accessible."
I find no technical advisory from L*I but this one is ICC
http://www.dli.pa.gov/ucc/Pages/Technical-Code-Advisories-International-Building-Code-2003.aspx
http://www.kmaccess.com/wp-content/uploads/2017/01/wheelchair_spaces_required_at-bars_2016_10_oct_bsj_final.pdf
A concise document from arizona regarding the issue.
https://www.phoenix.gov/pddsite/Documents/TRT/dsd_trt_pdf_00546.pdf