Exhibit 10.26
                                                                  EXECUTION COPY

                             FIRST AMENDMENT TO THE

                 AMENDED AND RESTATED COLLATERAL AGENT AGREEMENT

                                                       Dated as of July 12, 2004

          FIRST AMENDMENT TO THE AMENDED AND RESTATED COLLATERAL AGENT AGREEMENT
(the "AMENDMENT") among BUILDING MATERIALS CORPORATION OF AMERICA, a Delaware
corporation (the "COMPANY"), each other Subsidiary of the Company party to the
Collateral Agent Agreement referred to below (the "SUBSIDIARY PARTIES"),
CITICORP USA, INC., as 2003 Administrative Agent (as defined in the Collateral
Agent Agreement referred to below), each Senior Note Trustee (as defined in the
Collateral Agent Agreement referred to below), and CITIBANK, N.A., a national
banking association, as collateral agent under the Collateral Agent Agreement
referred to below (the "COLLATERAL AGENT").

          PRELIMINARY STATEMENTS:

     (1) Reference is made to the Credit Agreement, dated as of July 9, 2003 (as
amended by the First Amendment to the Credit Agreement, dated as of May 7, 2004,
and as otherwise amended, supplemented or otherwise modified through the date
hereof, the "CREDIT AGREEMENT"), among the Company, the lenders from time to
time party thereto, Citicorp USA, Inc., as administrative agent (the
"ADMINISTRATIVE AGENT") and Citigroup Global Markets Inc., as lead arranger.

     (2) Reference is also made to the Amended and Restated Collateral Agent
Agreement, dated as of July 9, 2003 (as amended, supplemented or otherwise
modified through the date hereof, the "COLLATERAL AGENT AGREEMENT"), among the
Company, the Subsidiary Parties, the Administrative Agent, the Collateral Agent
and each Senior Note Trustee (as defined therein).

     (3) Reference is further made to the Amended and Restated Security
Agreement, dated as of July 9, 2003 (as amended by the First Amendment to the
Amended and Restated Security Agreement, dated as of August 22, 2003, and the
Second Amendment to the Amended and Restated Security Agreement, dated as of May
7, 2004, and as otherwise amended, supplemented or otherwise modified through
the date hereof, the "SECURITY AGREEMENT"), among the Company, the Subsidiary
Parties and the Collateral Agent.

     (4) Capitalized terms not otherwise defined in this Amendment have the same
meanings as specified in the Collateral Agent Agreement or the Credit Agreement,
as applicable.

     (5) The parties hereto have agreed to amend the Collateral Agent Agreement
as hereinafter set forth.


<PAGE>
                                       2

          SECTION 1. AMENDMENTS TO THE COLLATERAL AGENT AGREEMENT. The
Collateral Agent Agreement is, effective as of the date hereof, and subject to
the satisfaction of the conditions precedent set forth in Section 2, hereby
amended as follows:

          (a)  The Recitals of the Collateral Agent Agreement are hereby amended
     by:

          (i)  deleting the word "and" at the end of Recital (B)(iv);

          (ii) adding a new Recital (B)(v) as follows:

               "(v) the Indenture to be entered by BMCA and a trustee to be
          selected by the Company, as trustee (the "NEW TRUSTEE"), pursuant to
          which senior notes due 2011 or 2014, at the Company's election, will
          be issued (the "NEW INDENTURE"), and"; and

          (iii) replacing Recital (B)(v) in its entirety with the following:

               "(vi) the Indenture, dated as of July 5, 2000, between BMCA and
          The Bank of New York, as trustee (the "2002 TRUSTEE", and collectively
          with the 2006 Trustee, the 2007 Trustee, the 2005 Trustee, the 2008
          Trustee, the New Trustee and any trustee in respect of any indenture
          pursuant to which Debt is issued to refinance any of the existing
          Senior Notes (as hereinafter defined) or which is otherwise permitted
          under the Credit Agreement and each of the other Senior Notes, the
          "SENIOR NOTE TRUSTEES"), pursuant to which the 10.50% senior notes due
          2002 were issued, as supplemented by a Supplement, dated as of
          December 4, 2000 (the "2002 INDENTURE", and collectively with the 2006
          Indenture, the 2007 Indenture, the 2005 Indenture, the 2008 Indenture,
          the New Indenture and any other indenture pursuant to which Debt is
          issued to refinance any of the existing Senior Notes (as hereinafter
          defined) or which is otherwise permitted under the Credit Agreement
          and each of the other Senior Notes, the "SENIOR NOTE INDENTURES").
          Payment of each Senior Note issued under each Senior Note Indenture is
          guaranteed by certain Subsidiaries of BMCA (each, a "SENIOR NOTE
          GUARANTOR") pursuant to Guaranties ("SENIOR NOTE GUARANTIES") executed
          in connection therewith or thereafter with respect thereto. The senior
          notes issued pursuant to the Senior Note Indentures (the "SENIOR
          NOTES") are and will be, from time to time, held by various holders
          (collectively, the "NOTEHOLDERS").".

          (b)  The Section beginning on page 2 entitled "Collateral Agency" is
     hereby amended by replacing the words "the Collateral" in the first line of
     the third paragraph thereof and in the second, third, fourth and sixth
     lines of the fourth paragraph thereof with the words "the Secured Debt
     Collateral".

          (c)  Section 1.1 of the Collateral Agent Agreement is hereby amended
     by inserting the following definitions in alphabetical order:

          "NEW INDENTURE": defined in Recital B.

          "NEW TRUSTEE": defined in Recital B."


<PAGE>
                                       3

          SECTION 2. CONDITIONS OF EFFECTIVENESS. This Amendment is subject to
the provisions of Section 9.1 of the Collateral Agent Agreement and Section 8.01
of the Credit Agreement. This Amendment shall become effective as of the date
first above written when, and only when, the Administrative Agent shall have
received counterparts of this Amendment executed by the Company, each Lender
Representative and the Collateral Agent.

          SECTION 3. REFERENCE TO AND EFFECT ON THE LOAN DOCUMENTS.(a) On and
after the effectiveness of this Amendment, each reference in the Collateral
Agent Agreement to "this Agreement", "hereunder", "hereof" or words of like
import referring to the Collateral Agent Agreement, and each reference in each
of the other Loan Documents to "the Collateral Agent Agreement", "thereunder",
"thereof" or words of like import referring to the Collateral Agent Agreement,
shall mean and be a reference to the Collateral Agent Agreement, as amended by
this Amendment.

          (b) The Collateral Agent Agreement, as specifically amended by this
Amendment, is and shall continue to be in full force and effect and is hereby in
all respects ratified and confirmed.

          (c) The execution, delivery and effectiveness of this Amendment shall
not, except as expressly provided herein, operate as a waiver of any right,
power or remedy of any Lender, the Administrative Agent, or the Collateral Agent
under any of the Loan Documents, nor constitute a waiver of any provision of any
of the Loan Documents.

          SECTION 4. COSTS AND EXPENSES. The Company agrees to pay on demand all
reasonable out-of-pocket costs and expenses of the Administrative Agent and
Collateral Agent in connection with the preparation, execution, delivery and
administration, modification and amendment of this Amendment (including, without
limitation, the reasonable fees and expenses of counsel for the Administrative
Agent and the Collateral Agent) in accordance with the terms of Section 8.04 of
the Credit Agreement and Section 5.3 of the Collateral Agent Agreement.

          SECTION 5. EXECUTION IN COUNTERPARTS. This Amendment may be executed
in any number of counterparts and by different parties hereto in separate
counterparts, each of which when so executed shall be deemed to be an original
and all of which taken together shall constitute but one and the same agreement.
Delivery of an executed counterpart of a signature page to this Amendment by
telecopier shall be effective as delivery of a manually executed counterpart of
this Amendment.

          SECTION 6. GOVERNING LAW. This Amendment shall be governed by, and
construed in accordance with, the laws of the State of New York.


<PAGE>
                                       4

                  IN WITNESS WHEREOF, the parties hereto have caused this
Amendment to be executed by their respective officers thereunto duly authorized,
as of the date first above written.

                                   BUILDING MATERIALS CORPORATION OF AMERICA


                                   By: /s/ John M. Maitner
                                      ------------------------------------------
                                   Name:  John M. Maitner
                                   Title: Vice President and Treasurer


                                   BMCA INSULATION PRODUCTS INC.
                                   BUILDING MATERIALS INVESTMENT CORPORATION
                                   BUILDING MATERIALS MANUFACTURING CORPORATION
                                   DUCTWORK MANUFACTURING CORPORATION
                                   GAF LEATHERBACK CORP.
                                   GAF MATERIALS CORPORATION (CANADA)
                                   GAF PREMIUM PRODUCTS INC.
                                   GAF REAL PROPERTIES, INC.
                                   GAFTECH CORPORATION
                                   LL BUILDING PRODUCTS INC.
                                   PEQUANNOCK VALLEY CLAIM SERVICE COMPANY, INC.
                                   SOUTH PONCA REALTY CORP.
                                   WIND GAP REAL PROPERTY ACQUISITION CORP.
                                   BMCA QUAKERTOWN INC.


                                   By: /s/ John M. Maitner
                                      ------------------------------------------
                                   Name:  John M. Maitner
                                   Title: Vice President and Treasurer




<PAGE>
                                       5

                                    CITIBANK, N.A., as Collateral Agent

                                    By:  /s/ Barbara L. Bennett
                                       -----------------------------------------
                                    Name:    Barbara L. Bennett
                                    Title:   Assistant Vice President



                                    CITICORP USA, INC., not individually, but
                                    solely as 2003 Administrative Agent

                                    By: /s/ Michael M. Schant
                                       -----------------------------------------
                                    Name:  Michael M. Schant
                                    Title: Vice President
                                           Asset Based Finance
                                           (212) 816-2432



<PAGE>
                                       6

                                    THE BANK OF NEW YORK, not
                                    individually, but solely as Senior
                                    Note Trustee under the 2006
                                    Indenture

                                    By: /s/ Kisha A. Holder
                                       -----------------------------------------
                                    Name:  Kisha A. Holder
                                    Title: Assistant Vice President


                                    THE BANK OF NEW YORK, not
                                    individually, but solely as Senior
                                    Note Trustee under the 2007
                                    Indenture

                                    By: /s/ Kisha A. Holder
                                       -----------------------------------------
                                    Name:  Kisha A. Holder
                                    Title: Assistant Vice President


                                    THE BANK OF NEW YORK, not
                                    individually, but solely as Senior
                                    Note Trustee under the 2005
                                    Indenture

                                    By: /s/ Kisha A. Holder
                                       -----------------------------------------
                                    Name:  Kisha A. Holder
                                    Title: Assistant Vice President


                                    THE BANK OF NEW YORK, not
                                    individually, but solely as Senior
                                    Note Trustee under the 2008
                                    Indenture

                                    By: /s/ Kisha A. Holder
                                       -----------------------------------------
                                    Name:  Kisha A. Holder
                                    Title: Assistant Vice President


                                    THE BANK OF NEW YORK, not
                                    individually, but solely as Senior
                                    Note Trustee under the 2002
                                    Indenture

                                    By: /s/ Kisha A. Holder
                                       -----------------------------------------
                                    Name: /s/ Kisha A. Holder
                                    Title: Assistant Vice President