UL 10C — Positive Pressure Fire Tests of Door Assemblies
UL 10C is the standard behind most US and Canadian fire door listings. What separates it from older neutral-pressure testing is the positive pressure condition and the hose stream test that follows the fire exposure — a doorset that survives the furnace but not the hose stream does not get the rating.
Positive pressure
UL 10C holds the furnace at a positive pressure relative to the surrounding space. This matters because hot gases are pushed towards the door rather than drawn away from it, so gaps and joints that stay closed under neutral pressure can leak. It is a closer representation of a real compartment fire.
The hose stream test
After the fire exposure the assembly is subjected to a water stream from a specified distance and nozzle. The test checks that the doorset still holds together when hit by a firefighting hose. Many assemblies that pass integrity in the furnace fail here, usually because the frame fixing or the leaf construction is not robust enough.
Ratings and assemblies
Ratings run from 20 to 180 minutes, with 45, 60 and 90 minutes the most common for commercial work. As in Europe, the report covers a specific assembly: frame gauge, leaf construction, hinges, closer, seals and the wall type it was installed in.
At a glance
- Positive pressure furnace, followed by hose stream test
- Ratings from 20 to 180 minutes
- Listed assembly includes frame, leaf, hardware and wall type
- NFPA 252 is the equivalent NFPA procedure
Common questions
What is the difference between UL 10B and UL 10C?
UL 10B is the older neutral-pressure test. UL 10C adds positive pressure and the hose stream requirement, and it is the one most current US specifications call up.
Does a UL listing cover doors made later?
It covers doors produced under the listing and factory follow-up service, built to the same drawings and materials as the tested assembly. Changing the core, skin gauge or hardware outside the listed design takes the product out of scope.
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