ARM 24.321.310. UNENCLOSED UNDERFLOOR AREAS

(1) All underfloor areas shall be enclosed to the ground in the same manner as required for exterior walls in ARM 24.321.308, unless such unenclosed areas are protected with either one-hour fire-resistance-rated construction or heavy timber construction or fire-retardant-treated wood to the underside of all exposed floors and all exposed structural columns, beams, and supporting walls. (2) If a structure is not located in a designated WUI, this rule does not apply.