Exhibit (a)(1)(Q)

NOTICE OF GUARANTEED DELIVERY

to

Tender Shares of Common Stock

(including the Associated Series A Participating Preferred Stock Purchase Rights)

of

ElkCorp

to

CGEA Investor, Inc.

a wholly owned subsidiary of

CGEA Holdings, Inc.

THE OFFER AND WITHDRAWAL RIGHTS EXPIRE AT MIDNIGHT, NEW YORK CITY TIME, ON FEBRUARY 14, 2007, UNLESS THE OFFER IS EXTENDED.

(Not be used for Signature Guarantees)

This Notice of Guaranteed Delivery, or a form substantially equivalent to this form, including the previously distributed Notice of Guaranteed Delivery, must be used to accept the Offer (as defined below) (i) if certificates evidencing shares of common stock, par value $1.00 per share (the “Shares”), of ElkCorp, a Delaware corporation (the “Company”), are not immediately available, (ii) if share certificates and all other required documents cannot be delivered to Mellon Investor Services LLC (the “Depositary”) or (iii) if the procedure for book-entry transfer cannot be completed on a timely basis or time will not permit all required documents to reach the Depositary on or prior to the Expiration Date (as defined in the Offer to Purchase, dated January 18, 2007 (the “Offer to Purchase”)). This Notice of Guaranteed Delivery may be delivered by hand or facsimile transmission or mail to the Depositary. See Section 3 of the Offer to Purchase, as supplemented by Section 3 of the Supplement (as defined below).

The Depositary For The Offer Is:

Mellon Investor Services LLC

By Mail:	By Overnight Courier:	By Hand:
Reorganization Department PO Box 3448 South Hackensack, NJ 07606 Attn: Reorganization Department	Reorganization Department 480 Washington Boulevard Mail Drop — Reorganization Jersey City, NJ 07310 Attn: Reorganization Department 27th Floor	Reorganization Department 120 Broadway, 13th Floor New York, NY 10271 Attn: Reorganization Department

By Facsimile Transmission:

(For Eligible Institutions Only)

(201) 680-4626

To Confirm Facsimile Only:

(201) 680-4860

DELIVERY OF THIS NOTICE OF GUARANTEED DELIVERY TO AN ADDRESS OTHER THAN AS SET FORTH ABOVE OR TRANSMISSION OF INSTRUCTIONS VIA FACSIMILE TRANSMISSION TO A NUMBER OTHER THAN AS LISTED ABOVE, DOES NOT CONSTITUTE A VALID DELIVERY TO THE DEPOSITARY.

THIS NOTICE OF GUARANTEED DELIVERY IS NOT TO BE USED TO GUARANTEE SIGNATURES. IF A SIGNATURE ON A LETTER OF TRANSMITTAL IS REQUIRED TO BE GUARANTEED BY AN “ELIGIBLE INSTITUTION” UNDER THE INSTRUCTIONS THERETO, SUCH SIGNATURE GUARANTEE MUST APPEAR IN THE APPLICABLE SPACE PROVIDED IN THE SIGNATURE BOX ON THE LETTER OF TRANSMITTAL.

Ladies and Gentlemen:

The undersigned hereby tenders to CGEA Investor, Inc. (“Purchaser”), a Delaware corporation and wholly owned subsidiary of CGEA Holdings, Inc. (“Parent”) upon the terms and subject to the conditions set forth in the Offer to Purchase, dated January 18, 2007, the related revised Letter of Transmittal and the Supplement thereto, dated January 22, 2007 (the “Supplement”) (which together, as amended, supplemented or otherwise modified from time to time, constitute the “Offer”), receipt of which is hereby acknowledged, the number of Shares specified below pursuant to the guaranteed delivery procedure set forth in Section 3 of the Offer to Purchase as supplemented by Section 3 of the Supplement.

Number of Shares:

Certificate Nos. (if available):

Check box if Shares will be tendered by book-entry transfer:  o

Account Number: 

Dated: _ _, 200  

Name(s) of Record Holder(s):

(Please Print)

Address(es): 

(Zip Code)

Area Code and Tel. No.: 

Signature(s): 

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GUARANTEE
(NOT TO BE USED FOR SIGNATURE GUARANTEES)

The undersigned, a firm which is a bank, broker, dealer, credit union, savings association or other entity that is a participant in the Security Transfer Agents Medallion Program, the New York Stock Exchange Medallion Signature Guarantee Program or the Stock Exchange Medallion Program or any other “eligible guarantor institution” (as such term is defined in Rule 17Ad-15 under the Securities Exchange Act of 1934, as amended), guarantees (a) that the above named person(s) “own(s)” the Shares tendered hereby within the meaning of Rule 14e-4 under the Securities Exchange Act of 1934, (b) that such tender of Shares complies with Rule 14e-4 and (c) delivery to the Depositary of the Shares tendered hereby, in proper form of transfer, or a Book-Entry Confirmation (as defined in the Offer to Purchase), together with a properly completed and duly executed Letter of Transmittal (or a manually signed facsimile thereof) with any required signature guarantees, or an Agent’s Message (as defined in the Offer to Purchase) in the case of a book-entry delivery, and any other required documents, within three New York Stock Exchange trading days after the date hereof.

The Eligible Institution that completes this form must communicate the guarantees to the Depositary and must deliver the Letter of Transmittal and certificates for Shares to the Depositary within the time period shown herein. Failure to do so could result in a financial loss to such Eligible Institution.

Name of Firm:

Address:

Zip Code

Area Code and Tel. No.: 

Authorized Signature

Name: 

Please Print

Title:

Dated: _ _, 200  

NOTE:  DO NOT SEND CERTIFICATES FOR SHARES WITH THIS NOTICE. CERTIFICATES SHOULD BE SENT ONLY WITH YOUR LETTER OF TRANSMITTAL.

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