EXHIBIT 32.3

                            CERTIFICATION PURSUANT TO
                      SECTION 906 OF THE SARBANES-OXLEY ACT

I, Robert J. Medlock, certify that:

            1.          I have reviewed this periodic report on Form 10-Q of NCI
                        Building Systems, Inc.;

            2.          This quarterly report fully complies with the
                        requirements of section 13(a) or 15(d) of the Securities
                        Exchange Act of 1934; and

            3           The information contained in this quarterly report
                        fairly presents, in all material respects, the financial
                        condition and results of operations of NCI Building
                        Systems, Inc.

Date:  September 15, 2003
                                           /s/ Robert J. Medlock
                                           -------------------------------------
                                           Robert J. Medlock
                                           Executive Vice President and Chief
                                           Financial Officer

A signed original of this written statement required by Section 906 has been
provided to NCI Building Systems, Inc. and will be retained by NCI Building
Systems, Inc. and furnished to the Securities and Exchange Commission or its
staff upon request.

This Certification shall not be deemed to be "filed" or part of the Report or
incorporated by reference into any of the registrant's filings with the
Securities and Exchange Commission by implication or by any reference in any
such filing to the Report.