What is the maximum number of risers allowed below the threshold of a door leading to an exterior landing?

The maximum number of risers allowed below the threshold of a door leading to an exterior landing is one riser. This standard is established to ensure safe and convenient access from the building to the exterior. A single riser makes it easier for occupants to navigate the transition from inside to outside, especially when carrying objects or for those with mobility challenges.

Having two risers could complicate the movement through the doorway, increasing the risk of tripping and falls, which is why building codes generally limit the height of thresholds to one riser. Therefore, this regulation focuses on accessibility and safety, making it essential to keep any changes in elevation minimal immediately at a door’s threshold when leading to an external landing.

The other choices, such as allowing no risers or multiple risers, do not align with establishing a smooth and safe transition at an entry point, which is a critical aspect of building safety design.