International Aluminum (IAL) 10-Q 2003 Q2 Quarterly report

Exhibit 99

CERTIFICATIONS PURSUANT TO 18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of International Aluminum Corporation (the “Company”) on Form 10-Q for the period ending December 31, 2002 as filed with the Securities and Exchange Commission (the “Report”), I, Cornelius C. Vanderstar, the Chairman of the Board and Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

1.The Report 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 Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: February 12, 2003	CORNELIUS C. VANDERSTAR
	Cornelius C. Vanderstar
	Chairman of the Board and
	Chief Executive Officer

In connection with the Quarterly Report of International Aluminum Corporation (the “Company”) on Form 10-Q for the period ending December 31, 2002 as filed with the Securities and Exchange Commission (the “Report”), I, Mitchell K. Fogelman, the Senior Vice President-Finance and Chief Financial Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

1.The Report 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 Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: February 12, 2003	MITCHELL K. FOGELMAN
	Mitchell K. Fogelman
	Senior Vice President — Finance
	and Chief Financial Officer

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