Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Fire-Resistance-Rated Assemblies
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### The governing rating shall always be confirmed with the Authority Having Jurisdiction before being locked onto the Contract Documents.
−### Each rated assembly shall be classified as a fire wall, fire barrier, fire partition, horizontal assembly, or shaft enclosure, because continuity and opening-protection rules differ by classification. {note}
+### Each rated assembly shall be classified as a fire wall, fire barrier, fire partition, horizontal assembly, or shaft enclosure, because continuity and opening-protection rules differ by classification.
```datasheet
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### IBC Section 1020 requires 0 hours for corridor walls in fully sprinklered Group A, B, E, F, M, S, and U occupancies, and 1 hour in non-sprinklered buildings and in Group I-2 and I-3 occupancies regardless of sprinklers. The 80-percent case in modern fully-sprinklered commercial work is a 0-hour corridor, which still must satisfy smoke-partition continuity even though it carries no fire-resistance rating. {note}
+### Corridor wall ratings shall be confirmed against the building's sprinkler status before any corridor wall is designated as rated.
+
```datasheet
label: Building Sprinkler Status
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```
−### Corridor wall ratings shall be confirmed against the building's sprinkler status before any corridor wall is designated as rated.
+### Rating inflation on the drawings shall be avoided; an assembly shall not be labeled rated where the governing code section requires no rating.
−### Rating inflation on the drawings shall be avoided; an assembly shall not be labeled rated where the governing code section requires no rating. {note}
−
### Labeling every corridor 1-hour in a fully sprinklered building where Section 1020 requires 0 hours needlessly raises cost and forces firestopping coordination at every conduit, pipe, and cable penetration that crosses the wall. {note}
### Shaft enclosure ratings shall follow IBC Section 713.4 based on the number of stories the shaft connects.
−### A shaft connecting fewer than four stories requires a minimum 1-hour enclosure; a shaft connecting four or more stories requires a minimum 2-hour enclosure. {note}
−
```datasheet
label: Shaft Enclosure Rating Basis (IBC 713.4)
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```
+### A shaft connecting fewer than four stories requires a minimum 1-hour enclosure; a shaft connecting four or more stories requires a minimum 2-hour enclosure. {note}
+
### The sprinkler substitution that reduces a 2-hour separation to 1-hour does not apply universally. {note}
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### The achieved rating depends on the stud gauge and spacing, the number and type of board layers, the board thickness, the fastener schedule, and any cavity insulation. Changing any one of these from the tested design can invalidate the rating or move the assembly to a different design number. {note}
−### Framing gauge and spacing shall match the tested design number; substituting a lighter or wider-spaced stud changes the applicable design and may reduce the rating. {note}
+### Framing gauge and spacing shall match the tested design number; substituting a lighter or wider-spaced stud changes the applicable design and may reduce the rating.
```datasheet
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### Where cavity insulation is part of the tested design, its presence, type, and thickness shall match that design.
−### Insulation affects both fire-resistance and acoustic performance in many UL and GA designs; substituting or omitting it can invalidate the listed rating. {note}
−
```datasheet
label: Cavity Insulation (per cited design)
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```
+### Insulation affects both fire-resistance and acoustic performance in many UL and GA designs; substituting or omitting it can invalidate the listed rating. {note}
+
### Non-symmetrical assemblies require a design that covers the exact two-sided configuration. {note}
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### Openings in a rated assembly shall be protected by opening protectives whose rating corresponds to the assembly rating per IBC Table 716.1.
−### A 1-hour barrier requires a 3/4-hour door; a 2-hour barrier requires a 1.5-hour door; a 3-hour barrier requires a 3-hour door or shutter; a 20-minute partition requires a 20-minute door. {note}
−
```datasheet
label: Opening Protective Rating (IBC Table 716.1)
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```
+### A 1-hour barrier requires a 3/4-hour door; a 2-hour barrier requires a 1.5-hour door; a 3-hour barrier requires a 3-hour door or shutter; a 20-minute partition requires a 20-minute door. {note}
+
### Opening protectives — rated doors, frames, glazing, and dampers — are governed by their own standards and shall be coordinated, not specified here. {note}
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### Through-penetrations of a rated assembly by pipe, conduit, cable, and duct shall be sealed with a tested firestop system that restores the assembly rating, per [[sync/firestopping]].
−### The finish rating of a tested design shall be observed where combustible structural elements are framed within the assembly. {note}
+### The finish rating of a tested design shall be observed where combustible structural elements are framed within the assembly.
### A UL design carries both a fire rating and a finish rating; the finish rating is the time before the unexposed face of the protective membrane reaches an average 250°F rise, and it is the life-safety metric that protects combustible framing inside the cavity. Overlooking the finish rating on a wood-framed rated wall is a substitution pitfall. {note}
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### Substituting any component of a listed assembly invalidates the tested rating unless a revised design number is selected. {note}
−### Changing the gypsum board manufacturer or thickness, the stud gauge, the insulation type, or the fastener schedule from what the listed design specifies breaks the chain of evidence that the assembly will perform. Each component shall match the cited listing, or a different design number that covers the substitution shall be selected and documented. {note}
+### Changing the gypsum board manufacturer or thickness, the stud gauge, the insulation type, or the fastener schedule from what the listed design specifies breaks the chain of evidence that the assembly will perform. Each component shall match the cited listing, or a different design number that covers the substitution shall be selected and documented.
### Any proposed substitution of a listed component shall be submitted as a revised design number with supporting listing documentation, and shall not be made in the field.
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### The fire-resistance rating of a code-compliant listed assembly is established by test, not by a manufacturer's warranty; the warranty here covers conformance of construction to the cited design. {note}