---
kind: "section"
citation: "30 C.F.R. § 57.22221"
title: "30"
number: "57.22221"
heading: "Overcast and undercast construction (I-A, II-A, III, and V-A mines)."
url: "https://uscodex.org/cfr/30/57.22221"
---

# §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;
- (c) **Kept clear of obstructions.**

## Notes

### Authority

Authority: 30 U.S.C. 811.

### Source

Source: 52 FR 24941, July 1, 1987, unless otherwise noted.

### Authority

Authority: 30 U.S.C. 811.

### Source

Source: 50 FR 4082, Jan. 29, 1985, unless otherwise noted.