A 1/2-in. low-profile threshold for single outswing Series 900 terrace doors meets Fair Housing Act accessibility standards, and is said to virtually eliminate floor-level protrusions to provide unobstructed passage for individuals using a cane, crutch, walker, or wheelchair. An optional 10-in. bottom door rail is available to further enhance accessibility. Even with the low threshold, the doors reportedly provide exceptional protection against invasive weather conditions. The doors are AW-PG 80-ATD AAMA rated, and have been ASTM E331 and E547 water tested. In addition, double weatherstripping within the doorframe mitigates air infiltration.