R311.3.1

Section R311.3.1 is titled 'Floor elevations at the required egress door' and covers the requirements for floor and/or landing elevations adjacent to exterior doors. Floor or landing elevation changes are required to not exceed a maximum dimension from the top of the door threshold. Also, where the exterior landings are not at grade, a ramp or stairway in compliance with this code must provide access to grade. The purpose of this section is to reduce the risk of trip and fall hazards. This section has an exception which increases the maximum elevation change dimension, where the door does not swing over the exterior floor or landing. The purpose of this exception is to allow for a safety 'trade-off', which may be used to provide other benefits, such as the prevention of rain or snow from entering the dwelling through the door.

The model shows side by side exterior doors with opposites swings for comparison. The thresholds, which are highlighted, are 1-1/2" high. The out swinging door has an exterior landing which is 1-1/2" below the top of the threshold; and the in swinging door has a landing that is 7-3/4" below the top of the threshold (which is allowed by the exception to this section). Also, one landing has stairs, and the other landing has a ramp to reach grade.