I have been waiting for someone to answer your question as I'd like to know the answer to use myself. Have you posted this question on the cleaning or gardening forums? People who garden have a lot of brick that mildews and may have the answer. If you get an answer, would you come back to this topic board and post it? Thanks

Last weekend the handle seized as it was pulled upward to lock the active door. After first removing, oiling and replacing the inside door handle, I repeated the process on the outside door handle with no luck. Today, I tried Kashmi's July 6, 2011 post regarding pushing out on the door while pushing down on the handle. This senior citizen had to alternate the pushing of door and handle, but with gradual movement of both. Finally gave it all I had left and the door opened! I've oiled the parts not accessible when the doors are closed and they operate better than when new. Thank you for the knowledge that it was not just this door lock that had jammed and the help to resolve the problem.

Ask the builder what the plans are.

Building a porch with steps down to the ground at the outer edge does make sense. If you leave as it I would suggest expanding the existing concrete stair the full width of the door opening. Looks odd as it is now. Good luck!