Where the solid-fuel heating appliance is placed on combustible flooring, noncombustible material as herein specified shall be placed beneath said appliance and extend a minimum of 18 inches beyond the appliance in all directions except the rear, which shall project a minimum of six inches beyond the appliance.
A. Where the "legs" or supportive members of a solid-fuel heating appliance elevate said appliance at least 18 inches above a combustible floor surface, a protective covering of twenty-four-gauge metal shall be placed under the appliance.
B. Where the supportive members are designed to elevate the appliance a distance of between six and 18 inches above a combustible floor surface, a protective covering of twenty-four-gauge sheet metal clad over one-fourth-inch-thick noncombustible stoveboard shall be placed under the appliance.
C. Where the supportive members are designed to elevate the appliance six inches or less above a combustible floor surface, a four-inch-thick hollow concrete masonry pad shall be placed or an approved noncombustible assembly of two-inch thickness.
D. Where a listed appliance specifies clearances different from those set forth in this section, the listed clearances shall apply.