Title 30

SECTION 57.22221

57.22221 Overcast and undercast construction (I-A, II-A, III, and V-A mines).

§ 57.22221 Overcast and undercast construction (I-A, II-A, III, and V-A mines).

Overcasts and undercasts shall be -

(a) Of substantial construction;

(b)(1) Constructed of noncombustible materials; or

(2) Where constructed of combustible materials, the outside surfaces shall be coated with at least one inch of construction plaster containing perlite and gypsum; at least one inch of expanded vermiculite, Portland cement and limestone; or other coatings with equivalent fire resistance;