Clear Space : Any area free of combustible materials. This does not preclude the storage of noncombustible materials that will not transmit an exposure fire
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}