Rack, Double-Row : Two single-row racks placed back-to-back having a combined width up to 12 ft (3. 7 m) with aisles at least 3. 5 ft (1. 1 m) on each side
NFPA 230 Standard for the Fire Protection of Storage 1999 ed. http://www.nfpa.org/assets/files/aboutthecodes/230 /230-f2002-rop.pdf, (Std: Fr Prac of Storage - Amer) {267 NFC}