Rationale

The proposed changes are with regards to the surface burning characteristics conditions of acceptance. Both the flame spread and smoke-developed index remain unchanged for fiber cement sheets used for calibration or supporting materials for ASTM E84. The condition of acceptance changed for fiber cement sheets used in cladding, façade, curtain wall, and soffit applications only. This is due to the fact that none of the model Codes have such stringent flame spread and smoke-developed requirements for any exterior wall coverings.