Perimeter Wall Shelving

Please clarify the 18-inch rule and how it pertains to storage on shelving lined up along the perimeter of a store room or office bookshelves along the walls.

In the Statement of Conditions™ (SOC) 3A, 6B (existing health care), and 3B, 6B (new health care), the Joint Commission requires clear space greater than or equal to 18 inches below sprinkler heads to the top of storage. This clear space should be a level plane greater than or equal to 18 inches below the sprinkler heads (diffuser or cover plate), without anything breaching this plane. A note in the SOC allows perimeter wall shelving and storage on that shelving in a sprinklered room to extend to the ceiling, provided that the storage or shelving is not directly below sprinkler heads. This note is based on an exception in NFPA 13, section 5.6.6, and Annex A, 13-A-5.6.6.