Unreasonable is not a term used in the Americans with Disabilities Act (ADA), but undue hardship is. An undue hardship analysis is based on several factors, including:

• the nature and cost of the accommodation needed;
• the overall financial resources of the facility making the reasonable accommodation, number of persons employed at this facility, and the effect on expenses and resources of the facility;
• the overall financial resources, size, number of employees, and type and location of facilities of the employer (if the facility involved in the reasonable accommodation is part of a larger entity);
• the type of operation of the employer, including the structure and functions of the workforce, the geographic separateness, and the administrative or fiscal relationship of the facility involved in making the accommodation to the employer; and
• the impact of the accommodation on the operation of the facility.

Your documentation should include all factors considered when making the undue hardship decision, along with objective evidence used in the determination.