(225 ILCS 705/31.26) (from Ch. 96 1/2, par. 3126)
    Sec. 31.26. Permanent overcasts shall be constructed of incombustible material such as masonry, concrete, concrete blocks, or metal and shall be of ample area to pass the required quantity of air, and where necessary to securely timber to prevent falls from the roof.
(Source: Laws 1953, p. 701.)