NFPA 285 governs the fire propagation characteristics of exterior wall assemblies that include combustible components. This article explains when it applies, how to design compliant systems, and what materials and strategies are typically used to meet code requirements in high-rise and mid-rise buildings.
When NFPA 285 is Required
- Exterior walls containing foam plastic insulation or combustible WRBs
- Commercial buildings greater than 40 feet in height
- Walls using metal composite material (MCM) cladding or high-pressure laminate (HPL) systems
- Any project using combustible elements in exterior walls must be evaluated
Designing a Compliant Wall Assembly
- Reference tested assemblies from ICC-ES, UL, or Intertek directories
- Use non-combustible claddings (masonry, fiber cement, metal) or fire-tested MCM panels
- Include continuous mineral wool or other non-combustible insulation where possible
- Choose fire-rated WRBs such as gypsum-faced membranes or fluid-applied barriers with test reports
Firestopping and Detailing Requirements
- Install firestopping at floor lines using mineral wool or firestopping caulks/sprays
- Use UL-listed joint systems between wall and floor slab edges
- Coordinate with structural engineer and code consultant on required ratings
- Label fire-resistive joints clearly in construction documents and field QA
Inspection and Documentation
- Submit full wall assembly documentation showing NFPA 285 compliance
- Label each tested system and maintain traceability of installed components
- Photograph firestopping at each floor line during QA walkthroughs
- Coordinate special inspections where local codes require it
Always consult the AHJ (Authority Having Jurisdiction) early in design to avoid costly redesigns or delays.
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