What UL 263 measures
A full-size assembly is built into a furnace — a vertical furnace for walls and partitions, a horizontal furnace for floors, roofs and ceilings — and exposed to the standard time–temperature curve. The rating is the time for which the assembly keeps meeting all criteria.
Standard fire curve (selected points): 538 °C (1000 °F) at 5 min, 704 °C (1300 °F) at 10 min, 843 °C (1550 °F) at 30 min, 927 °C (1700 °F) at 1 h, 1010 °C (1850 °F) at 2 h, 1052 °C (1925 °F) at 3 h, 1093 °C (2000 °F) at 4 h.
Main acceptance criteria:
- no passage of flame or gases hot enough to ignite cotton waste on the unexposed side;
- temperature rise on the unexposed surface no more than 139 °C (250 °F) on average and 181 °C (325 °F) at any single point;
- load-bearing assemblies carry their applied load for the rating period;
- walls and partitions withstand the hose stream test after the fire exposure.
Typical products
Wall and partition systems, curtain wall and façade spandrels, floor–ceiling and roof–ceiling assemblies, fire protection of steel beams, and the walls and roofs of modular buildings, battery energy storage enclosures and data centre containers.
Why tests fail
Most failures are not in the core material but at joints, fixings and penetrations, where hot gas finds a path or the unexposed side heats faster than expected. We review drawings before the test and can run an indicative test to find weaknesses before the certification test.
Frequently asked questions
What is the difference between UL 263 and ASTM E119?
They describe the same fire exposure, acceptance criteria and test procedure and are kept technically aligned. UL 263 is the UL-published version used in UL certification and listings; ASTM E119 is often cited directly in codes and specifications. We are accredited for both.
Which ratings can be tested?
Ratings are given in hours or fractions of an hour — typically 30 minutes up to 4 hours — depending on how long the assembly meets the criteria under the standard time–temperature curve.
Can you test load-bearing assemblies?
Load-bearing floors, roofs and beams are within scope. Load-bearing columns, load-bearing fire walls and fire partitions are excluded from our accreditation.