Evaluation Report Does Not Match the Wall Assembly
A two-story Type II-B office building is proposed with an exterior wall 8 feet from the property line. The wall is required to have a 1-hour fire-resistance rating. The contractor submits an ICC-ES evaluation report for a wood-frame wall assembly. The report states that the assembly with one layer of 5/8-inch Type X gypsum board on the interior has a 45-minute fire-resistance rating; a 1-hour rating is achieved only with two layers. The submitted plans and shop drawings show one layer. The contractor argues that the evaluation report is an approved alternate material and that the inspector cannot reject it. The building is unsprinklered. The inspector must decide whether the proposed wall complies and what documentation is needed before the wall can be approved.
1. What is the code basis for accepting the proposed wall, and does the evaluation report alone make it compliant?
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IBC Section 104.11 permits alternate materials and methods where the building official finds that the proposed design complies with the code's intent. IBC Section 703.2 requires fire-resistance ratings to be established by tested assemblies or listed designs. An ICC-ES evaluation report is evidence that a specific assembly has been evaluated, but it does not approve every variation of that assembly. The report shows a 45-minute rating for one layer of gypsum board. The code requires 1 hour. Therefore, the report alone does not make the submitted one-layer wall compliant; the contractor must install the configuration that achieved the 1-hour rating or submit a different listed assembly.
2. What should the inspector require before approving the wall?
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The inspector should require a revised wall assembly that matches a listed or tested 1-hour design. That could be the two-layer configuration described in the evaluation report, a different listed assembly, or an approved alternate supported by test data. The submittal should include the evaluation report or listing, the manufacturer's installation instructions, and details showing gypsum board thickness, fastener spacing, stud size and spacing, and any required insulation. The inspector should also verify fireblocking and penetration protection. The contractor's argument that the inspector cannot reject an evaluation report is incorrect; the inspector must confirm that the installed assembly matches the report's tested configuration.
3. If the contractor installs the two-layer assembly but omits the insulation shown in the report, can the inspector accept it?
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No, not without documentation. Fire-resistance-rated assemblies are tested as complete systems. If the evaluation report or listing requires insulation as part of the assembly, omitting it changes the assembly and invalidates the basis for the rating. The inspector should require the contractor to install the assembly exactly as listed or provide an approved alternate that demonstrates a 1-hour rating without insulation. The inspector should document the nonconformance and require re-inspection after correction. This is a materials-and-systems acceptance issue, not a judgment call about whether insulation is generally good practice.