A residential building inspector is reviewing plans for a new dwelling located in a wildland-urban interface (WUI) area. The plans specify the use of exterior wall coverings. What is the minimum fire-resistance requirement for the exterior wall covering in this WUI area?
- AClass A fire-resistance rating
- BClass B fire-resistance rating
- CClass C fire-resistance rating
- DNo specific fire-resistance rating is required for exterior wall coverings.
Show answer & explanationAnswer & explanation
Correct answer: D. No specific fire-resistance rating is required for exterior wall coverings.
According to the 2021 IRC, Section R337 (Wildland-Urban Interface Fire Area), while specific requirements exist for ignition-resistant construction, including materials for exterior walls, there is no blanket requirement for exterior wall coverings to have a Class A, B, or C fire-resistance rating. The code focuses on specific materials and assemblies that are ignition-resistant, rather than a surface burning characteristic rating typically applied to interior finishes or roofing.
Why the other options are wrong
- A. Class A ratings are typically for roofing or interior finishes with high fire resistance.
- B. Class B ratings are typically for roofing or interior finishes with moderate fire resistance.
- C. Class C ratings are typically for roofing or interior finishes with light fire resistance.
WUI Exterior Wall Covering
Requirements for exterior wall materials in wildland-urban interface areas, designed to resist ignition from wildland fires.
- Focuses on ignition resistance, not surface burning characteristics.
- Includes specific material types and assembly details.
- Specified in IRC Section R337.
Memory trick: WUI homes need fire-wise walls, not a class, just strong materials for all.