Direct answer: UL 10B and UL 10C are both fire-test standards for door assemblies, but they use different furnace-pressure conditions. The applicable standard depends on the product category, its listing, the opening, and the adopted code. UL Solutions’ current application guide identifies rolling steel fire doors under category GSVV with UL 10B; its positive-pressure UL 10C category is for certain swinging fire doors. Do not assume every fire-rated shutter needs UL 10C.
The distinction that matters
| Check | UL 10B | UL 10C |
|---|---|---|
| Standard | Fire Tests of Door Assemblies | Positive Pressure Fire Tests of Door Assemblies |
| Pressure approach | Conventional fire-door furnace-pressure regime | Positive pressure above the prescribed neutral-pressure plane |
| Test purpose | Evaluate a complete fire-door assembly | Evaluate a complete assembly under the specified positive-pressure conditions |
| How to use the result | Match the listing and rating to the exact opening | Use where the adopted code and certified product category call for it |
Both are assembly tests, not a certification of an isolated slat, motor, or curtain material. Their temperature exposure and hose-stream procedures have similarities, but a result under one standard is not a blanket approval under the other.
Why a rolling shutter is a special case
The term “fire door” covers several constructions. UL’s fire-door application guide lists Rolling Steel Fire Doors (GSVV): UL 10B and separately lists Swinging-type Fire Doors, Positive-pressure Tested (GSZN): UL 10C. That classification is a practical reason to check the actual listing before copying a specification from a swinging-door project into a rolling-shutter project.
A buyer should request the listing or certification record for the complete proposed assembly, including its size range, guides, bottom bar, operator, release arrangement, and rating. A laboratory report for a different size or product configuration does not establish that the offered unit is covered. The wall or barrier rating alone also does not determine the opening-protective rating; the adopted building code’s opening table and the authority having jurisdiction (AHJ) control that decision.
Positive pressure is not “across the entire specimen”
UL 10C specifies a neutral-pressure plane and positive furnace pressure above it. Describing the whole specimen as being under positive pressure is inaccurate. Pressure at different heights and the prescribed measurement location matter when interpreting a test, so project documents should name the test standard and the certified assembly instead of using “positive-pressure tested” as a generic marketing term.
A four-step specification check
- Identify the rated wall, opening function, and adopted code edition. Ask the design professional or AHJ for the required opening-protective rating and any smoke or egress condition.
- Identify the shutter type. A rolling steel fire door, service-counter shutter, fire curtain, and swinging fire door may sit in different certification categories.
- Ask the supplier for a current certification or listing covering the exact product family, rating, clear opening size, operator, and installation details. Confirm which fire-test standard appears in that record.
- Specify installation, release, inspection, and maintenance to the listing and the locally adopted edition of NFPA 80. Do not substitute an EN/CE declaration for a North American listing without the AHJ’s acceptance.
For product options, see RHIDOOR’s rolling shutter doors and fire and security doors. Product pages describe available families; request model-specific certification before specifying a fire-rated unit.
Frequently asked questions
Does UL 10C replace UL 10B for every fire shutter?
No. UL’s application guide identifies rolling steel fire doors under UL 10B. Some code applications require positive-pressure-tested swinging fire doors. Verify the product category and adopted code for the specific opening.
Is NFPA 252 withdrawn?
No. NFPA lists a 2022 edition of NFPA 252, Standard Methods of Fire Tests of Door Assemblies. UL also lists NFPA 252 among the test standards applicable to fire doors and shutters.
Can a UL 10C label on a component certify the whole shutter?
No. Ask for the certification covering the complete assembly in its installed configuration. Components must match the assembly listing and installation instructions.
Does an EN 1634-1 result count as a UL listing?
Not automatically. The test and certification routes differ. The project’s AHJ decides whether a proposed alternative is acceptable under the adopted code.
References
- UL Solutions: Fire-rated doors and opening protectives application guide — product categories GSVV and GSZN.
- UL Solutions: Fire-resistance rating and opening protectives — UL 10B, UL 10C, and NFPA 252.
- NFPA LiNK: Available publications — NFPA 252 edition listing.
Confirm the current listing and local code before procurement or installation.