It looks like this IRS page says that elevators do not qualify...
"Qualified retail improvement property:
Generally, this is any improvement to an interior portion of nonresidential real property if it meets the following requirements.
1. The portion is open to the general public and is used in the retail trade or business of selling tangible property to the general public.
2. The improvement is placed in service more than 3 years after the date the building was first placed in service.
3. The expenses are not for the enlargement of the building, any elevator or escalator
, any structural components benefiting a common area, or the internal structural framework of the building."
THank you so much.