I have a patio and an inside floor at about the same height.
Water often runs under the threshold and is rotting out the door frame and baseboards.
Once you've created this ridge, wrap the remaining sealer tightly against the edge of the threshold. Before the door gets put in place, you need to place a bead of latex caulking between the siding and the trim on top of the bituthane, all along the door opening. Now when you put the door back in place, it will drop onto the caulking and cut-off mastic, sealing its perimeter and keeping water from infiltrating, even if it does penetrate the siding. This Old House and the This Old House window and This Old House Online are trademarks of WGBH Educational Foundation. Neither WGBH Educational Foundation nor PBS endorses any product or service mentioned within This Old House Online or any web sites linked to or from This Old House Online.