Final answer:
The answer addresses the building code requirement for exterior door landings. The landing cannot be more than ½ inch lower than the threshold if the door does not swing over it, according to the International Residential Code (IRC) and the Americans with Disabilities Act (ADA).
Step-by-step explanation:
The question pertains to a building code requirement for the installation of exterior doors.
According to the International Residential Code (IRC) and the Americans with Disabilities Act (ADA), the landing area outside an exterior door should not be more than ½ inch (0.5 inches) lower than the threshold of the door if the door does not swing over the landing. This regulation is in place to ensure safety and accessibility.
The landing must be level with or slightly below the threshold to provide a safe and accessible path. The exact requirement may vary depending on local building codes, but the ½ inch rule is a common standard to avoid tripping hazards and to ensure that individuals with disabilities can access the entrance comfortably.