What are the key changes in Chapter 4 Special Detailed Requirements Based On Occupancy & Use of CBC 2025?

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

Lovekush Gangwar Dec 01, 2025 Updated Sep 25, 2026 4 min read M↓

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

Section	Topic	Description of Change	Impact
403.2.2.1	Wall Assembly Materials	Reorganized requirements for interior wall structural impact resistance at shafts/stairways.	Clarifies and standardizes high-rise wall assembly approvals.
403.2.2.4	Glass Walls in High-Rises	New criteria added.	Allows innovative façade/atrium glazing with safety criteria.
403.3.1	Sprinkler Risers	Now allows a single express riser for buildings under 420 ft.	Reduces cost for mid-rise/high-rise projects.
403.5.3	Stairway Door Operation	Mandatory unlocking on power failure; fire alarm; FCC signal.	Enhances firefighter access and life safety.
404.6 Exception 5	Atrium Enclosures	In I-2 and R-2.1, 3-story atriums may omit fire barriers if smoke control accounts for adjoining spaces.	Increased design flexibility in healthcare/residential care.
404.10	Exit Stairways in Atriums	New condition: discharge must comply with §1928.1.	Aligns atrium discharge with exit discharge rules.
404.12	Group I & R-2.1 Means of Egress	Egress from treatment rooms may not pass through an atrium.	Prevents unsafe reliance on atrium path for assisted-care egress.
407.4.4.1	Exit Access through Care Suites	2022 mid-cycle amendment removed for CA; requirement struck.	Deletes conflicting/overlapping CA amendment.
407.4.4.3	Corridor Access, Group I-2	Completely rewritten; includes: max. 100 ft travel inside suite, limits on intervening rooms, sprinkler exceptions.	Major redesign implications for I-2 patient care floors.
408.13	I-3 Windows	Updated security glazing standards.	Stronger break resistance standards for correctional facilities.
408.16	Vehicle Sallyports, I-3	Requires NFPA 13 sprinklers + 2-hr fire barrier unless roof ≥50% open.	Raises safety for secure prisoner transport.
410.2.4	Proscenium Wall	Exception allows new rated assemblies in Type I buildings.	More flexibility for theaters/performing arts buildings.
411.3	Amusement Area Detection	Detection/alarm requirements moved from §907.12.1–§907.2.12.3.	Consolidates amusement area rules for clarity.
411.4.1	Exit Marking	Photoluminescent exit signs required.	Modernizes visual egress cueing in dark ride spaces.
411.6	Flammable Decorative Materials	Commissioned to §806 compliance.	Improves consistency across chapters.
414	Hazardous Materials	Revisions to tables and quantities.	Must re-evaluate all hazmat storage designs.
420.2	Separation Walls	Clarifies walls between sleeping units & dwelling units must also be fire partitions.	Ensures adequate vertical separation in multi-family.
420.3	Horizontal Separation	Floor assemblies separating sleeping from dwelling units must meet §711.	Strengthens sound/fire separations.
422.7	Domestic Cooking in Ambulatory Care	Building must be fully sprinklered; cooking areas must be fire-partitioned.	Reduces common fire risk in healthcare kitchens.
423.4.1 & 423.5.1	Storm Shelters	Adds design occupant capacity requirements.	Aligns CA with ICC/NSSA storm shelter standards.

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).
‍

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

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