EXHIBIT 99.1

                   CERTIFICATE OF THE CHIEF EXECUTIVE OFFICER
                                   OF ELKCORP

      Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 (18 U.S.C.ss.
1350):

      I, Thomas D. Karol, Chief Executive Officer of ElkCorp, certify to my
knowledge and belief pursuant to Section 906 of Sarbanes-Oxley Act of 2002 (18
U.S.C.ss. 1350) that:

      (1)   The Quarterly Report on Form 10-Q for the period ended December 31,
            2002, which this statement accompanies, fully complies with the
            requirements of section 13(a) or 15(d) of the Securities Exchange
            Act of 1934; and

      (2)   The information contained in the Quarterly Report on Form 10-Q for
            the period ended December 31, 2002 fairly presents, in all material
            respects, the financial condition and results of operations of
            ElkCorp.

Date: February 3, 2003
                                             By  /s/ Thomas D. Karol
                                                 ----------------------------
                                                     Thomas D. Karol
                                                     Chief Executive Officer