AMENDMENT NO. 1 TO LOCK-UP AND VOTING AGREEMENT

EXHIBIT 2.3

AMENDMENT NO. 1
TO LOCK-UP AND VOTING AGREEMENT

     This AMENDMENT NO. 1 (this “ Amendment ”), dated as of October 8, 2009, to the Lock-Up and Voting Agreement, dated as of August 31, 2009 (the “ Lock-Up Agreement ”), is by and among the Persons executing this Amendment as “Requisite Consenting Creditors” on the signature pages hereto and NCI Building Systems, Inc. (the “ Company ”). Unless otherwise specifically defined herein, each term used herein shall have the meaning assigned to such term in the Lock-Up Agreement.

RECITALS

     WHEREAS, the Company desires to modify certain economic terms of the Transactions as specified herein and the parties hereto desire to amend the Lock-Up Agreement to permit such modifications;

     WHEREAS, Section 6.7 of the Lock-Up Agreement provides for the amendment of the Lock-Up Agreement in accordance with the terms set forth therein by an instrument in writing signed by the Requisite Consenting Creditors; and

     WHEREAS, this Amendment constitutes such an instrument in writing, and has been signed by the Requisite Consenting Creditors.

     NOW, THEREFORE, in consideration of the foregoing and for other good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the Company and the Consenting Creditors hereto (constituting the Requisite Consenting Lenders) hereby agree as follows:

     Section 1. References to Lock-Up Agreement . Each reference in the Lock-Up Agreement to “hereof,” “herein,” “hereunder,” “hereby”, “hereto” and “this Agreement” shall, from and after the date hereof, refer to the Lock-Up Agreement as amended by this Amendment.

     Section 2. Amendment to Section 2.1 . Clause (1) of the first sentence of Section 2.1 of the Lock-Up Agreement is hereby amended and restated in its entirety to read as follows:

. . . (1) the economic terms of the transactions contemplated by the Amended Investment Agreement, after giving effect to the matters referred to on Schedule B hereto (including the Offer, the Prepayment, the Restatement and the Investment, after giving effect to the matters referred to on Schedule B hereto, collectively, the “ Transactions ”) are not altered or amended in a manner adverse to the Consenting Noteholders, . . .

     Section 3. Amendment to Definition of the “Transactions” . For all purposes of the Lock-Up Agreement, the term “Transactions” shall have the meaning ascribed to it in clause (1) of Section 2.1 of the Lock-Up Agreement, as amended pursuant to this Amendment.

     Section 4. Amendment to Section 2.3 . Section 2.3 of the Lock-Up Agreement is hereby amended by inserting the phrase “after giving effect to the matters referred to on Schedule B hereto” after each use in such section of the term “Amended Investment Agreement”.

     Section 5. Amendment to Section 4.3 . Section 4.3 of the Lock-Up Agreement is hereby amended by inserting the phrase “unless the Securities received by each Consenting Creditor in the Offer or pursuant to the bankruptcy plan are registered” after the words “If the Restructuring is completed pursuant to the Offer or, if the Restructuring is completed through a prepackaged bankruptcy and the Securities received by the Consenting Creditors are not freely tradeable pursuant to the provisions of section 1145 of the Bankruptcy Code.”

     Section 6. Representations and Warranties . Each of the Consenting Creditors signatory hereto and the Company represents and warrants that the representations and warranties set forth in Sections 3.1 and 3.2 of the Lock-Up Agreement, respectively, of the Lock-Up Agreement are true and complete on the date hereof as if made on and as of the date hereof (or, if any such representation or warranty is expressly stated to have been made as of a specific date, such representation or warranty shall be true and correct as of such specific date), and as if each reference in said Sections 3.1 and 3.2 to “this Agreement” included reference to this Amendment.

     Section 7. Conditions Precedent . This Amendment shall become effective as of the date of this Amendment upon receipt by the Company of counterparts of this Amendment executed by the Company and Consenting Lenders party to the Lock-Up Agreement constituting the Requisite Consenting Lenders.

     Section 8. Effect of the Amendment . Each of the Company and the Requisite Consenting Creditors acknowledges and agrees that nothing contained herein shall, by implication or otherwise, be deemed to constitute a waiver of or consent to any other term, provision or condition of the Lock-Up Agreement or limit, impair or prejudice any right or remedy that any party hereto may have or may in the future have under the Lock-Up Agreement, which shall remain in full force and effect, and the Consenting Creditors hereby reserve all such rights and remedies. Except as set forth herein, the terms, provisions and conditions of the Lock-Up Agreement shall remain unchanged and in full force and effect.

     Section 9. Miscellaneous . Article VI of the Lock-Up Agreement shall apply to this Amendment, mutatis mutandis .

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     IN WITNESS WHEREOF, each party hereto has caused this Amendment to be signed as of the date first above written.

[Signature page to Amendment No. 1 to Lock-Up and Voting Agreement]

     IN WITNESS WHEREOF, each party hereto has caused this Amendment to be signed as of the date first above written.

CONSENTING NOTEHOLDERS :

[Signature page to Amendment No. 1 to Lock-Up and Voting Agreement]

SCHEDULE B ¹

     1. Upon the effectiveness of the Restatement on the Closing Date, the Lenders that execute the new credit agreement (in the form of the Form of Amended Credit Agreement after giving effect to the matters referred to in this Schedule B ) prior to the filing of the Prepackaged Plan shall receive a consent fee equal to 2.0% of the aggregate principal amount of Loans held by such Lenders that is prepaid pursuant to the Prepayment, in addition to the consent fee previously offered by the Company equal to 2.0% of the aggregate principal amount of Loans held by such Lenders that remain outstanding after giving effect to the Prepayment. Such fees shall be paid to the Administrative Agent for the account of such Lenders. Such fees together comprise the total consent fee to be paid to such Lenders with respect to the Restatement and related transactions.

     2. The definition of the term “Applicable Margin” in the Form of Amended Credit Agreement will be modified (a) to substitute “5.00% per annum” for “4.00% per annum” with respect to ABR Loans, and “6.00% per annum” for “5.00% per annum” with respect to Eurocurrency Loans, respectively, in clause (i) thereof, and (b) to insert the phrase “ending on or after October 30, 2011” after the phrase “most recently completed fiscal quarter of the Borrower” in clause (ii) thereof.

     3. The following definition will be added to the Form of Amended Credit Agreement in appropriate alphabetical order:

     “ 2009 Tax Refund ”: any U.S. federal or state income tax refund received by the Borrower or any Subsidiary thereof (inclu