Guards and Window Fall Protection | CRC § R312


The following sections from the California Residential Code pertain to the safety measures and precautions required for various architectural elements in a residential building. These include provisions for guards (protective barriers) at open-sided walking surfaces, specifications for the height of these guards, restrictions on the size of openings in these guards, and specific requirements related to window opening heights and emergency escape measures.

Let's clarify some key terms and phrases to help you understand these provisions better:

  • Guards: These are protective barriers installed on open-sided walking surfaces (like stairs, porches, balconies, landings, and ramps) that prevent falls. They are crucial in areas where the vertical drop is more than 30 inches within 36 inches of the edge.
  • Walking Surface: This is any surface in a building where people might walk, including floors, stairs, ramps, landings, and more.
  • Nosing: The nosing of a stair is the edge of the stair tread (the part of the stair you step on) that protrudes over the riser (the vertical part of the stair). It's often mentioned in guard height measurements on stairs.
  • Opening Limitations: These regulations dictate the maximum size of openings in the guards to prevent small children from slipping through. The measurements refer to the diameter of a hypothetical sphere that should not be able to pass through the openings.
  • Operable Window: An operable window is one that can be opened and closed. The codes outline specific safety precautions for these windows, especially if they are located near the floor or significantly above the ground outside.
  • ASTM F2090: This is a standard set by ASTM International, which specifies safety requirements for window fall prevention devices for non-emergency escape (egress) windows and window fall prevention devices with emergency escape (egress) release mechanisms.
  • Emergency Escape and Rescue Openings: These are windows or other openings that can be used as an exit route in case of emergencies, such as a fire. The code lays out specifications for such openings, which should not be obstructed by any window opening control device or fall prevention device.

With these terms in mind, the upcoming code sections will give you detailed guidelines on how to meet these safety requirements in different parts of a residential building. 


Guards shall be provided in accordance with CRC R312.1.1 through R312.1.4. Guards shall be provided for those portions of open-sided walking surfaces, including floors, stairs, ramps and landings that are located more than 30 inches (762 mm) measured vertically to the floor or grade below at any point within 36 inches (914 mm) horizontally to the edge of the open side. Insect screening shall not be considered as a guard.


Required guards at open-sided walking surfaces, including stairs, porches, balconies or landings, shall be not less than 42 inches (1067 mm) in height as measured vertically above the adjacent walking surface or the line connecting the nosings.


  1. Guards on the open sides of stairs shall have a height of not less than 34 inches (864 mm) measured vertically from a line connecting the nosings.
  2. Where the top of the guard serves as a handrail on the open sides of stairs, the top of the guard shall be not less than 34 inches (864 mm) and not more than 38 inches (965 mm) as measured vertically from a line connecting the nosings.

Opening Limitations

Required guards shall not have openings from the walking surface to the required guard height that allow passage of a sphere 4 inches (102 mm) in diameter.


  1. The triangular openings at the open side of stair, formed by the riser, tread and bottom rail of a guard, shall not allow passage of a sphere 6 inches (153 mm) in diameter.
  2. Guards on the open side of stairs shall not have openings that allow passage of a sphere 43/8 inches (111 mm) in diameter.

Window Opening Height

In dwelling units, where the bottom of the clear opening of an operable window opening is located less than 24 inches (610 mm) above the finished floor and greater than 72 inches (1829 mm) above the finished grade or other surface below on the exterior of the building, the operable window shall comply with one of the following:

  1. Operable window openings will not allow a 4-inchdiameter (102 mm) sphere to pass through where the openings are in their largest opened position.
  2. Operable windows are provided with window opening control devices or fall prevention devices that comply with ASTM F2090.

Emergency Escape and Rescue Openings

Where an operable window serves as an emergency escape and rescue opening, a window opening control device or fall prevention device, after operation to release the control device or fall prevention device allowing the window to fully open, shall not reduce the net clear opening area of the window unit to less than the area required by sections R310 Emergency and Escape Rescue Openings.