R312.1.3

Section R312.1.3 is titled 'Opening limitations' and covers the requirements for the size of openings within the area of a required guard. The size limitation and method for making the measurement are established. The purpose of this section is to reduce fall and entrapment hazards. This section has two exceptions. The first exception allows for an increase in opening size below the bottom rail of a guard on stairways. The purpose of this exception is to allow for practical construction geometry. The second exception allows for an increase in opening size for the other areas of guards on stairs. The purpose of this exception is to allow for practical construction geometry and aesthetic considerations. To elaborate, treads and risers are allowed a 3/8" variance within a flight, so spindles are allowed this increase in order for a stairway tread/riser pattern and guard spindles pattern to remain consistent and aesthetically pleasing, (because stairways are often a focal point of a dwelling). Neither exception is considered to diminish the level of safety.

The model shows guards on an elevated walking surface and stairway. The three sphere sizes restricted by this section and two exceptions are shown not being able to pass through their related areas of the guard, making this model compliant with this section of the code.