A vehicular body structure includes a polymeric deck panel. The deck panel includes adjacent ridges and valleys with legs shared therebetween, crossbeam footprints crosswise to the adjacent ridges and valleys, and ribs extending along the adjacent ridges and valleys between the crossbeam footprints and ending short thereof. The ribs project normally to the deck panel past the ridges, and have elongate cross-sectional shapes, with cross-sectional thicknesses substantially the same as or greater than the cross-sectional thicknesses of the adjacent ridges and valleys.