A method for manufacturing a one-piece woven (OPW) air bag includes providing yarns and warping the yarns on at least one beam of a loom. Yarns are simultaneously woven into a fabric air bag structure having two layer portions defining both an inflatable volume and non-inflatable portions and single layer portions forming seams delimiting the inflatable volume. The air bag structure is cut to define the OPW air bag and at least one opening extending through only one layer of the two layer portions.