Disclosed herein is an interior structural assembly for a vehicle. The assembly includes a defrost panel forming at least a portion of a defrost duct, the defrost panel has first and second panel extensions laterally extending at opposite ends of a defrost base and an instrument panel overlaying the defrost panel, the instrument panel having at least one defrost aperture and first and second ends generally horizontally extending across the interior width of the vehicle, wherein the first and second panel extensions extend to the first and second ends of the instrument panel, respectively.