“A-1” Occupancy Fire-Retardant Interior Finishes

General Definition

Fire-retardant interior finishes refer to materials used for walls, ceilings, and other interior surfaces that are treated to limit flame spread and smoke development in case of fire.
- In Group A-1 occupancies (e.g., theaters, auditoriums, concert halls), these materials reduce fire propagation, improve visibility during evacuation, and minimize toxic smoke exposure.

Element	IBC Table 803.11 (USA) – Fire-Retardant Interior Finishes	BSL Article 35 (Japan) – Interior Finish Fire Protection
Surface Flame Spread Index (Walls & Ceilings)	– ≤25 flame spread index (Class A).	– Stricter—≤20 flame spread index (more fire-resistant).
Smoke Developed Index	– ≤450 smoke developed index.	– Stricter—≤300 smoke developed index to reduce visibility obstruction.
Fire-Retardant Coating Requirements	– Coatings allowed for flame spread reduction.	– Stricter—coatings must be factory-applied and tested.
Interior Finish Classifications	– Class A, B, or C based on flame spread and smoke index.	– More stringent classification system ensuring lower flame spread and smoke release.
Testing & Certification Standards	– Materials must be tested per ASTM E84 or UL 723.	– Materials must be tested per ISO 5660 or Japan Fire Testing Center (JFTC) standards.

Surface Flame Spread Index (Walls & Ceilings):
- IBC allows materials with a flame spread index of ≤25 (Class A).
- BSL enforces stricter limits, allowing only materials with a flame spread index of ≤20.
Smoke Developed Index:
- IBC sets a maximum smoke developed index of 450.
- BSL enforces a stricter limit of 300 to minimize smoke buildup during evacuation.
Fire-Retardant Coating Requirements:
- IBC allows field-applied coatings to improve fire resistance.
- BSL mandates that fire-retardant coatings must be factory-applied and pre-tested. (Stricter requirement.)
Interior Finish Classifications:
- IBC classifies materials as Class A, B, or C based on fire spread and smoke development.
- BSL applies more stringent material classifications to ensure lower flame spread and smoke release.
Testing & Certification Standards:
- IBC relies on ASTM E84 or UL 723 test methods.
- BSL requires compliance with ISO 5660 or Japan Fire Testing Center (JFTC) standards.

Issue	IBC Recommendation	BSL Recommendation
Lower Surface Flame Spread Index	Reduce maximum allowable flame spread index from 25 to 20, aligning with BSL.	Maintain stricter flame spread index but allow for alternative compliance paths.
Stronger Smoke Development Limits	Reduce smoke developed index from 450 to 300 to enhance occupant safety.	Maintain strict smoke development limits but clarify exceptions for specialty materials.
Stricter Fire-Retardant Coating Requirements	Require fire-retardant coatings to be factory-applied and tested.	Improve testing regulations for field-applied coatings in existing buildings.

Surface Flame Spread Index (Walls & Ceilings):
- IBC allows up to 25 (Class A).
- BSL enforces a stricter limit of 20.

Smoke Developed Index:
- IBC allows up to 450.
- BSL enforces a stricter limit of 300. (Better smoke control.)

Fire-Retardant Coating Requirements:
- IBC allows field-applied coatings.
- BSL enforces stricter factory-applied coating requirements.

Interior Finish Classifications:
- IBC uses Class A, B, and C designations.
- BSL enforces more stringent classifications to reduce fire spread.

Testing & Certification Standards:
- IBC relies on ASTM E84 and UL 723.
- BSL enforces ISO 5660 and Japan Fire Testing Center (JFTC) standards.

BSL enforces stricter fire-retardant interior finish requirements than IBC for A-1 occupancies.
BSL allows only materials with a lower flame spread index (≤20), while IBC permits up to 25.
BSL enforces a lower smoke developed index (≤300) to minimize smoke hazards, while IBC allows up to 450.
BSL mandates fire-retardant coatings to be factory-applied, whereas IBC allows field application.
Both IBC and BSL require rigorous testing, but BSL enforces stricter compliance with ISO 5660 and JFTC standards.