A doorway with a sill attachment that increases a sill DP rating includes spaced vertical jambs, a head jamb, and a sill, all of which form a door frame, and a door panel mounted in the frame. The sill is a substantially hollow contain-and-drain type sill with a nosing provided with drainage openings. a substantially hollow sill attachment is mounted to and extends along the nosing and the attachment projects downwardly to a position below the openings in the nosing of the sill. The drainage openings communicate with the interior of the extension. Weep holes that communicate with the environment are located in the sill attachment at a position below the openings in the nosing of the sill. The sill and sill attachment may be formed as a single component, or as separate components assembled either in the factory or the field. The attachment increases a column height of water that can be accommodated by the sill before leakage occurs, and thus enhances the DP rating of the sill.