1. Between intake and return air courses, except temporary controls may be used in rooms that are 600 feet or less from the centerline of the entry from which the room was developed. Unless otherwise approved by the Chief, these stoppings shall be maintained to and including the third connecting crosscut outby the working face.
B. Permanent stoppings shall be built of substantial, incombustible material such as concrete, concrete blocks, brick, tile, or other approved material; however, where physical conditions prohibit the use of such materials, timbers laid longitudinally “skin to skin” may be used.
Code 1950, § 45-60.4; 1954, c. 191; 1966, c. 594, § 45.1-59; 1978, c. 729; 1994, c. 28; 1996, c. 774.