Unpierced Wall 1 : A wall in which all pipes or conduits that pass through are sealed to prevent the flow of air, and in which windows are glazed with safety glass or wired glass
Ralph W. Burklin & Robert G. Purington, Fire Terms: A Guide to Their Meaning and Use, National Protection Association, Boston, MA 1980 USA. (Guide: Meaning and Use, Nat Prot Association Fr Srvc - Amer) {457}