In accordance with the Architectural Barriers Act (ABA) of 1968, all new or reconstructed facilities that are built, bought, rented, or leased by or on behalf of a Federal agency are to be accessible.

The various accessibility guidelines do allow a very few exceptions. These exceptions include:

UFAS 4.1.4 (1) General Exceptions : "Accessibility is not required to elevator pits, elevator penthouses, mechanical rooms, piping or equipment catwalks, lookout galleries, electrical and telephone closets, and general utility rooms."

and

ADAAG 4.1.3 Exception 2 : "Elevator pits, elevator penthouses, mechanical rooms, piping or equipment catwalks are exempted".

From the ADA/ABA Accessibility Guidelines Chapter 2 F203 General Exceptions :

• Construction sites directly associated with the process of construction (including, but not limited to: scaffolding, hoists, materials storage).
  
  
• Raised areas primarily used for security, life safety, or fire safety (including, but not limited to: lookout galleries, prison guard towers, fire towers).
  
  
• Limited Access Spaces: including spaces served only by ladders, catwalks, and crawl spaces.
  
  
• Machinery spaces: including, but not limited to: elevator pits and penthouses, mechanical, electrical and communications equipment rooms, water treatment or sewage pump rooms, electric substations, and transformer vaults.
  
  
• Single Occupant Structures accessed only by below grade or elevated access: including, but not limited to toll booths accessed by underground tunnels.

Forest Service Handbook 7309.11.34.16.1.g also details a few very specific exemptions to accessibility requirements in new and existing Forest Service buildings. These include observation galleries, mechanical equipment rooms, and spaces or facilities designed for use by employees needing considerable dexterity and special abilities. Please check the Forest Service Handbook for details about these limited exceptions.