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Got a CRC R321.2 correction?

Window fall protection devices

For builders in California, Greater Seattle, the Las Vegas area, the Denver area and Kansas City · CrossBeam Permits

What this code requires, how to fix it, and how cities and counties review it

What this code requires

CRC R321.2 requires window opening control devices (WOCDs) on windows where the bottom of the clear opening is less than 24 inches above the finished floor and the window sill is more than 72 inches above the finished exterior grade below. The device must comply with ASTM F2090 and restrict the opening enough that a 4-inch sphere cannot pass through. The intent is fall prevention for children — a child can fall through a window opening that's close to the floor and high off the ground before anyone nearby can react. Where the same window is also required as an emergency escape and rescue opening (EERO), the WOCD must still allow the window to be fully opened from the inside to meet the EERO minimum clear area requirements.

How to fix it

  1. Add sill height and exterior grade columns to the window schedule

    The window schedule needs two additional data columns: "sill height AFF" (above finished floor) and "sill height above exterior grade." Measure or calculate the sill height from the finished floor to the bottom of the clear opening for each window. Then determine the exterior grade elevation directly below each window from the grading plan or site section. Any window with sill height AFF under 24 inches AND sill height above grade over 72 inches is a qualifying window. Mark those rows clearly — "Fall protection required per CRC R321.2" — in the schedule.

  2. Specify ASTM F2090-compliant WOCDs on qualifying windows

    In the window schedule or the specifications, call out the WOCD by standard: "Window opening control device complying with ASTM F2090, restricting clear opening to prevent passage of a 4-inch sphere." Name the manufacturer and model if known — Andersen, Marvin, Simonton, and most major window manufacturers offer ASTM F2090-compliant hardware. Vague notes like "window stop" or "window restrictor" are not enough for plan check. The ASTM F2090 reference must appear verbatim.

  3. Address the EERO override for any qualifying bedroom windows

    If a qualifying window is also the required emergency escape and rescue opening for a sleeping room, the WOCD spec must confirm that the device allows the window to be fully opened from the interior without tools or special knowledge. ASTM F2090 includes a release-force provision (a maximum 15-pound release force) specifically to allow egress. Add a note on the window schedule for those windows: "WOCD per ASTM F2090; device allows full EERO opening from interior — min. 5.7 sq ft net clear area maintained." Cross-reference the EERO dimensions in the egress schedule if you maintain one.

  4. Add a general note to the window and door schedule sheet

    Place a general note on the sheet containing the window schedule: "Windows where the clear opening bottom is less than 24 inches above finished floor and the sill is more than 72 inches above exterior grade shall limit openings so a 4-inch sphere cannot pass, or be provided with window opening control devices or fall prevention devices complying with ASTM F2090. See schedule for qualifying windows." This note tells the plan-checker exactly where to look and what code governs it.

  5. Show the exterior grade at each qualifying window on the site section or elevation

    Plan-checkers sometimes need to verify the 72-inch exterior grade measurement. On the exterior elevations or building sections, dimension from finished exterior grade to the bottom of the clear opening for any window you've flagged as qualifying. If the grade slopes, use the grade directly below the window at the wall face. This avoids back-and-forth on whether the measurement was taken correctly.

  6. Review windows on additions that change exterior grade conditions

    If the project involves an addition or significant regrading, check whether any existing windows on the structure now meet the dual-threshold trigger under the new grade conditions. A window that previously sat 6 feet above a flat grade might now be 8 feet above a finished cut slope. Flag those windows in the schedule and add WOCDs if they qualify. It's better to catch this before plan check than to get a corrections letter on windows that weren't part of the work scope.

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Why you got flagged

Here's why plan-checkers flag this section on corrections letters: the two-condition trigger (floor height AND exterior grade height) is easy to miss when the window schedule only lists opening dimensions without connecting them to what's outside the wall.

The most common correction is a missing WOCD designation in the window schedule. Plan-checkers look for every window on the schedule to be evaluated against both thresholds: sill height from finished floor (under 24 inches triggers the requirement) and the sill height above exterior grade (over 72 inches confirms it). When the window schedule uses a standard format that tracks only rough opening size and glazing type, neither measurement gets documented. The plan-checker can't verify compliance, so a correction goes out. This happens constantly on master bedroom and second-floor bedroom windows that happen to have low sills.

A second pattern is a WOCD note that doesn't reference ASTM F2090. Saying "window safety stop per manufacturer" or "window restrictor provided" isn't enough. The code specifically requires compliance with ASTM F2090, a test standard that verifies the device limits the opening to block a 4-inch sphere while still meeting a minimum force-to-release requirement. If the spec block or general notes don't call out ASTM F2090 by name, the plan-checker will flag it.

A third scenario comes up on bedroom windows that serve as the required EERO. Designers sometimes add the WOCD requirement correctly but don't address the EERO override — the plans show a WOCD but don't note that the device allows full opening from the interior for emergency egress. That's a dual-purpose window and both functions need to be shown as compatible. The WOCD spec needs to explicitly state it complies with ASTM F2090's release-force provisions, which exist precisely so the device can be defeated from the inside.

The official code

2025 California Residential Code R321.2 — Window Fall Protection

Read the source →

Common questions

What windows require fall protection devices under CRC R321.2?
Both conditions must be true at the same time: the bottom of the clear opening must be less than 24 inches above the finished floor inside the room, AND the window sill must be more than 72 inches (6 feet) above the finished exterior grade below the window. If either condition isn't met, R321.2 doesn't apply to that window. So a low-sill window on the ground floor typically won't trigger it because the exterior grade is close to the window. A second-floor bedroom window with a low sill almost always triggers it.
What does ASTM F2090 actually require for a window opening control device?
ASTM F2090 is the test standard for window opening control devices. It has two main requirements: first, when engaged, the device must limit the window opening enough that a 4-inch sphere cannot pass through — this is the child fall-prevention function. Second, the device must release with no more than 15 pounds of force applied from the interior — this preserves emergency egress. The release requirement is why WOCDs can coexist with emergency escape windows. Any device that passes ASTM F2090 testing meets both of these criteria. When specifying hardware, the manufacturer should be able to provide an ASTM F2090 compliance statement — ask for it before ordering.
Can a bedroom window have a WOCD and still serve as the emergency escape opening?
Yes, that's exactly what the EERO exception in R321.2 is designed for. A window that both triggers the fall-protection requirement and serves as the required emergency escape and rescue opening must have an ASTM F2090-compliant WOCD installed. The device must allow the window to be fully opened from the interior — no tools, no special knowledge — so the full EERO minimum clear area (5.7 square feet, minimum 24 inches high and 20 inches wide) is achievable in an emergency. The ASTM F2090 release-force limit ensures a child or adult can override the device from inside. Show both functions on the window schedule notes.
Does R321.2 apply to ADU projects?
Yes. R321.2 applies to any new residential construction under the California Residential Code, which includes new ADUs and additions. If an ADU has a second-floor bedroom or a loft with a low-sill window more than 6 feet above grade, qualifying windows need WOCDs. ADU window schedules are often minimal — just a simple table with rough openings and U-factors for energy compliance. Add the sill height AFF and exterior grade height columns before submitting, or expect a correction.
Is there a maximum opening size a WOCD allows, or just the 4-inch sphere rule?
The code doesn't set a fixed maximum opening dimension — the standard is the 4-inch sphere test from ASTM F2090. In practice, most compliant devices limit the opening to roughly 3.5 to 4 inches of net clear opening width when engaged. That's enough for ventilation but not enough for a child to fall through. The only fixed dimension the code cares about is that a 4-inch sphere cannot pass when the device is in the restricted position.
What if the window sill is at 22 inches AFF but the building is single-story — do I still need a WOCD?
Only if the window is also more than 72 inches above the finished exterior grade. A window at 22 inches AFF on a single-story home at grade level is usually 8 to 10 feet above grade, which clears the 72-inch threshold — so yes, both conditions would be met and a WOCD is required. But if that same window has its sill at 5 feet above grade for some reason (grade slopes steeply toward the building, or it's a basement window in a cut), the exterior grade condition isn't met and the WOCD isn't required. Run the numbers for each window individually.
Does the WOCD need to be shown on the architectural plans or just in the specs?
It needs to appear in both places for a clean plan check approval. The window schedule on the architectural plans should identify qualifying windows and note 'WOCD per ASTM F2090 required.' The spec section or window schedule general notes should call out the ASTM F2090 standard explicitly. Some plan-checkers also want to see the device called out on the window type detail if the schedule uses window type marks rather than a full schedule. Cross-referencing both the schedule and the notes is the fastest path to approval — missing one of the two is a common reason for a returned correction.
Does R321.2 apply to existing windows on a residential addition project?
It depends on whether the addition changes the grade conditions at the existing windows. R321.2 applies to new construction, but if an addition raises the structure — adding a second story, for example — existing windows on the addition side can suddenly sit more than 72 inches above the finished exterior grade where they didn't before. Plan-checkers reviewing the addition may flag those existing windows if the new grading plan shows the grade has dropped or the window is now much higher relative to the exterior. Adding WOCDs to those windows becomes part of the addition scope. Check the exterior grade elevation at each low-sill window on the structure and run the two-condition test before you submit.

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