Parking lots are considered parking facilities per the 2010 ADA Standard, Section 208.2 and Advisory 208.2.

Where more than one parking facility is provided on a site, the number of accessible spaces provided on the site shall be calculated according to the number of spaces required for each parking facility. Table 208.2 Parking Spaces”.

 If parking is provided for Self-Parking by employees or visitors or both then accessible spaces are required to be provided for each parking facility per the 1991 Standard, Section 4.1.2(5)(a).

"Where a total of four or fewer parking spaces, including accessible parking spaces, are provided on a site, identification of accessible parking spaces shall not be required” per the 2010 ADA Section 216.Signs, 216.5 Parking, Exceptions 1.

Per Title I of the ADA employees with disabilities are entitled to reasonable accommodations in the workplace. These accommodations may include items such as modifications to the parking and/or providing more than the minimum required accessible parking spaces. http://www.eeoc.com/guidance/discrimination/disability-discrimination/

Question: Are employee parking lots considered parking facilities under the 2010 Standards requiring accessible spaces? 

Answer: Yes, parking lots are considered parking facilities per the 2010 ADA Standard, Section 208.2 and Advisory 208.2.

Question: Is there a difference between parking spaces marked or reserved for employees and parking spaces that are just in the back of the building, unmarked but intended for employees?

Answer: If parking for the public or employees is provided ( marked or unmarked) it is subject to the requirements of the 2010 ADA, Table 208.2. To answer the question more direct would require more information but to start, the difference between marked and unmarked employee parking may be the signage, paint, paving, striping and accessible route.

If the parking in back of the building is a separate facility from other parking on site the number of accessible spaces provided on the site shall be calculated according to the number of spaces required for each parking facility. See the 2010 ADA, Section 208.2 Table 208.2 Parking Spaces, and the 1991 Standard, Section 4.1.2(5)(a),

Because the question is involving employee’s it may be subject to Title 1 requirements for reasonable accommodations.

If parking for the public or employees is provided (marked or unmarked) it is subject to the requirements of the 2010 ADA, Table 208.2.