A side curtain airbag assembly includes an airbag cushion having a length and a height; a wrapper sheet having a length extending along the airbag cushion and a width perpendicular to the length; and a plurality of mounting strips distributed along the length. Each mounting strip includes a mounting bracket; a wrapping strip; and a connector strap. The wrapper sheet extends across at least two of the mounting strips and is affixed to the airbag cushion by at least one seam composed of stitches. The stitches divide the length of the wrapper sheet into a first partial width and a second partial width of the wrapper sheet. The first partial width of the wrapper sheet has a plurality of cutout openings distributed along an outer edge extending along the length of the wrapper sheet and aligned with the mounting strips. The second partial width can be free of cutout openings.