Chapter 4 sees substantial changes, especially for high-rise buildings, atriums, care suites in I-2 occupancies, hazardous materials, and special amusement areas.

The most significant changes include:

• New glass wall rules for high-rise buildings
• Revised stairway re-entry door operation requirements
• Expanded atrium enclosure exceptions (especially for I-2/R-2.1)
• New vehicle sallyport requirements for I-3
• Relocation of special amusement area alarm requirements
• Significant rewrites for care suite egress and access rules
• Updates throughout hazardous material sections
  
  

Full Detailed Table Of All Changes  -  Chapter 4

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Expert Commentary  -  Why Chapter 4 Is Influential

1. Healthcare (I-2) sees major changes

The rewritten care suite rules fundamentally impact:

• Nurse station placement
• Corridor access
• Travel distances
• Patient room access sequences

Architects designing hospitals will need to revisit standard floor templates.

2. Atrium flexibility increased

Especially for medical and R-2.1 occupancies  -  a big benefit for designers wanting open, daylighted multistory spaces in care environments.

3. High-rise and tall buildings get new glazing & stair door rules

These are based on post-incident analyses and help ensure:

• Firefighter re-entry
  
• Reduced smoke-floor infiltration
  
• Safer glass failure modes
  

4. New sallyport rules

Correctional facilities will see stricter requirements, particularly around fire spread in enclosed vehicle transfer zones.

FAQs

1. What types of buildings are most affected by the 2025 Chapter 4 changes?

The most impacted occupancies include high-rise buildings, healthcare facilities (I-2), residential care (R-2.1), correctional facilities (I-3), and any building with atriums or hazardous materials. These groups see the largest revisions in egress, fire protection, glazing, and smoke control rules.

2. What is the biggest change for healthcare projects?

The complete rewrite of care suite egress and corridor access requirements (§407.4.4.3).
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This change affects:

• Maximum internal travel distances
  
• Allowed intervening spaces
  
• Access to corridors
  
• Sprinkler and smoke control interactions
  

Hospitals and medical designers will need to re-evaluate typical floor layouts and care suite configurations.

3. How do the new high-rise glass wall rules affect design?

Section 403.2.2.4 introduces new criteria for glass walls in high-rise buildings, allowing more innovative atrium and façade glazing while applying stricter safety and performance requirements. This enables design flexibility but requires earlier structural and fire-life-safety coordination.

4. What changed regarding stair door re-entry in high-rises?

Section 403.5.3 now requires stairway doors to unlock under:

• Power failure
  
• Fire alarm activation
  
• Fire Command Center (FCC) signal
  

This enhances firefighter access and prevents entrapment during emergencies.

5. How did atrium design rules change?

A major new exception allows I-2 and R-2.1 buildings to omit certain fire barriers for 3-story atriums if the smoke control system accounts for the adjoining spaces. This enables more open, daylighted designs, especially in healthcare or assisted-living facilities.

6. What’s new for correctional facility vehicle sallyports?

Section 408.16 now requires:

• NFPA 13 sprinklers
  
• A 2-hour fire barrier‍

Unless the roof is at least 50% open to the outdoors. This significantly increases fire protection requirements for enclosed transfer areas.

7. Which amusement area rules were relocated?

Detection and alarm rules moved from scattered locations in 907.2.12.1–907.2.12.3 into a unified location at §411.3, making amusement area compliance easier to interpret and enforce.

8. Do the hazardous materials sections change significantly?

Yes. Chapter 4’s hazmat sections were updated with revised tables, thresholds, and classifications, requiring designers to re-evaluate maximum allowable quantities and storage room design early in the project.

9. How do the changes affect multifamily residential buildings?

Sections 420.2 and 420.3 clarify that walls between sleeping units and dwelling units must be fire partitions, and horizontal separations must comply with §711. This strengthens fire/sound separation requirements in multi-family housing.

10. Are these changes more about safety or flexibility?

Both.

• High-rise and correctional updates focus on life safety.
  
• Atrium and care suite revisions introduce significant design flexibility while clarifying long-confusing rules.
  
• Hazardous materials updates aim at consistency and modern standards.

References

1. ‍2022 California Building Code, Title 24, Part 2 (Volumes 1 & 2) with July 2024 Supplement updated

2. 2025 California Building Code Volumes 1 and 2, Title 24, Part 2