Kepatuhan Tahan Api Baja Berdasarkan Standar IBC 722523

When project teams specify fire protection for complex steel structures such as trusses, they must reconcile building-code interpretation with construction detailing. Under the International Building Code and local amendments, determining the required thickness of spray-applied fire-resistive materials depends on documented testing, prescriptive provisions, or engineering analysis.

Fire protection code context

Under the International Building Code and local codes such as the Chicago Building Code, certain building elements are required to meet specific fire-resistance ratings. In Type I-C construction, roof-supporting beams, girders and trusses are typically required to achieve a one-hour fire-resistance rating.

The codes also include a height-based exemption: roof-support members located 20 feet (about 6.1 meters) or more above the floor may not require additional fire protection. When such members are below that threshold, the fire-resistance requirement must be enforced strictly. Designers and contractors must then rely on recognized ANSI/UL design details to establish the material type, minimum thickness and design basis needed for fire-plan review.

Three routes for determining fire protection thickness

When a directly matching UL design detail is not available, engineering practice generally follows three routes to establish spray-applied fire-resistive material thickness in compliance with building-code requirements.

Route	Core basis	Application note
Fire test results	Experimental data based on relevant ASTM standards	Test conditions must fully match the actual member
Prescriptive code provisions	Requirements under IBC Section 722.5.2.3	Apply the calculation or design method provided by the code
Engineering design analysis	Steel temperature calculation based on thermal analysis	Thickness is determined by a professional engineer

Key compliance considerations

Several common misconceptions can undermine a fire-protection specification during code review.

Manufacturer authority: Fire-protective material manufacturers may offer recommendations, but they do not have the authority to define the minimum thickness that satisfies the building code.
Limits of ICC-ES reports: An ICC-ES report cannot by itself substitute for code requirements. Any use must trace back to the underlying test method or calculation basis and confirm that it fits one of the three compliant routes.
Validity of UL reports: A UL report carries legal weight only when it is based on the necessary ASTM test standards. Designers should verify whether the report covers the specific member sizes and geometries involved, including angles and gusset plates.

For complex trusses, those checks are especially important because connections and built-up sections can alter heat-transfer assumptions. A design basis that does not address the actual steel geometry may not satisfy fire-review requirements even when it references a recognized product or report.

Frequently Asked Questions

What if no exact UL design detail matches the project?

If no directly matching UL detail is available, the preferred options are a thermal analysis performed by a qualified professional engineer or an evaluation under the prescriptive provisions of IBC Section 722.5.2.3. The resulting approach should be documented in a written report that expressly cites the applicable ASTM test standard or calculation model, rather than relying only on manufacturer literature.

Why can an ICC-ES report not serve as the direct basis for fire-protection thickness?

An ICC-ES report is generally an evaluation of product performance, not a fire-protection design for a specific project. It may cover multiple application scenarios, but if it does not state the thickness required for the steel-member geometry in a given project, it cannot by itself meet the fire-review requirement for a design basis.

What special requirements apply to complex trusses with angles and gusset plates?

Complex connections can change the steel section's heated perimeter-to-area ratio, often referred to as the W/D ratio. The fire-protection design must ensure that the applied thickness covers all heated surfaces and that thickness is calculated for the worst-case member section so the assembly can achieve the overall one-hour fire-resistance rating.