An underlayment not tested as part of a fire-resistance-rated roof assembly is proposed as an additional component. Under 2021 IBC 703.2.1.4, what is required?
- AAccept it automatically because underlayments are exempt from assembly fire-resistance requirements.
- Provide sufficient data to the building official showing that the required fire-resistance rating is not reduced.
- CUse only its thermal R-value to establish fire-resistance compliance.
- DAssume adding any layer always increases the assembly rating.
Where to look it up
https://core-docs.s3.amazonaws.com/documents/asset/uploaded_file/3836/Lennox/3042180/2021_International_Building_Code.pdf
Why B is correct
Supplemental materials not included in the tested assembly require supporting data showing no reduction in the required rating. The code does not create a blanket underlayment exemption, nor does it infer assembly performance from one component alone. Source: 2021 IBC 703.2.1.4; https://core-docs.s3.amazonaws.com/documents/asset/uploaded_file/3836/Lennox/3042180/2021_International_Building_Code.pdf