Exhibit 10.42  SECURITY AGREEMENT
SUPPLEMENT  March 26, 2007  Deutsche Bank AG New York Branch, as the Collateral
Agent for
the Secured Parties referred to in the
Credit Agreement referred to below 60 Wall Street, MS  NYC 60-0208 New York, New York 
10005 
Attn: Marguerite Sutton  Reference is made to (i) the Junior Lien Term
Loan Agreement dated as of March 15, 2007 (as amended, restated,
supplemented, waived or otherwise modified, refinanced or replaced from time to
time, the Loan
Agreement), among Building Materials Corporation of America, a
Delaware corporation, and certain of its Subsidiaries, as the Borrowers, the
Lenders party thereto, Deutsche Bank AG New York Branch (DBNY),
as administrative agent for the Lenders, and (ii) the Amended and Restated
Security Agreement dated March 15, 2007 (as amended, restated,
supplemented, waived or otherwise modified, refinanced or replaced from time to
time, the Security
Agreement) made by the Grantors from time to time party thereto
in favor of DBNY (together with any successor collateral agent appointed
pursuant to the Collateral Agency Agreement, the Collateral Agent) for the Secured
Parties. Terms defined in the Credit Agreement or the Security Agreement and
not otherwise defined herein are used herein as defined in the Loan Agreement
or the Security Agreement.  SECTION 1.  Grant of Security. Each
of the undersigned (each an Additional Grantor)
hereby grants to the Collateral Agent, for the ratable benefit of the Secured
Parties, a security interest in all of its right, title and interest in and to
the Collateral owned by such Additional Grantor.  SECTION 2.  Security for Obligations.
The grant of a security interest in, the Collateral by each Additional Grantor
under this Security Agreement Supplement secures the payment of all Secured
Obligations of such Additional Grantor now or hereafter existing under or in
respect of the Loan Documents, whether direct or indirect, absolute or
contingent, and whether for principal, reimbursement obligations, interest,
premiums, penalties, fees, indemnifications, contract causes of action, costs,
expenses or otherwise. Without limiting the generality of the foregoing, this
Security Agreement Supplement and the Security Agreement secures the payment of
all amounts that constitute part of the Secured Obligations and that would be
owed by such Additional Grantor to any Secured Party under the Loan Documents
but for the fact that such Secured Obligations are unenforceable or not
allowable due to the existence of a bankruptcy, reorganization or similar
proceeding involving a Loan Party.


SECTION 3.  Representations and
Warranties. Each Additional Grantors exact legal name, location, chief
executive office, type of organization, jurisdiction of organization and
organizational identification number is set forth in Schedule I hereto.  SECTION 4.   Covenants.   Within 30 days after the date hereof (or as
otherwise agreed by the Collateral Agent) (i), each Additional Grantor shall
provide to the Collateral Agent the following, as of such date:  (A)  A schedule setting forththe Equity Interests of such Additional
Grantor and the Initial Pledged Debt of such Additional Grantor.  (B)  A schedule setting forth the Intellectual
Property of such Additional Grantor, if any.  (C)  A schedule setting forth all deposit
accounts of such Additional Grantor.  (D)  A schedule setting forth all of the
commercial tort claims of such Additional Grantor.  (E)  A schedule setting forth all of the
Equipment and Inventory of such Additional Grantor.  (F)  A schedule setting forth any letter of
credit for which such Additional Grantor is a beneficiary or assignee.  (ii)  Each
Additional Grantor shall make each other representation and warranty set forth
in Section 6 of the Security Agreement with respect to itself and the
Collateral granted by it.  SECTION 5.  Obligations Under the
Security Agreement. Except as otherwise set forth herein, each Additional
Grantor hereby agrees, as of the date first above written, to be bound as a
Grantor by all of the terms and provisions of the Security Agreement to the
same extent as each of the other Grantors. Each Grantor further agrees, as of
the date first above written, that each reference in the Security Agreement to
an Additional Grantor or a Grantor shall also mean and be a reference to
such Additional Grantor, that each reference to the Collateral or any part
thereof shall also mean and be a reference to such Additional Grantors
Collateral or part thereof, as the case may be, and that each reference in the
Security Agreement to a Schedule shall also mean and be a reference to the
schedules attached hereto.  2


SECTION 6.  Governing Law. This
Security Agreement Supplement shall be governed by, and construed in accordance
with, the laws of the State of New York.  Very truly yours,ElkcorpElk Premium Building
  Products, Inc.Elk Corporation of AmericaElk Corporation of AlabamaElk Corporation of TexasElk Corporation of
  ArkansasElk Performance Nonwoven
  Fabrics, Inc.Elk Composite Building
  Products, Inc.RGM Products, Inc.Ridgemate Manufacturing
  Co. Inc.Elk Slate
  Products, Inc.Elk VersaShield Building
  Solutions, Inc.Elk Technology
  Group, Inc.Chromium CorporationElk Technologies, Inc.Midland Path
  Forward, Inc.Lufkin Path
  Forward, Inc.Elk Group, Inc.Elk Group, L.P.NELPA, Inc.By
  /s/ John F. Rebele/Title:
  Senior Vice President,
  Cheif Financial Officer and
  Cheif Administrative OfficerAddress for notices:1361 Alps RoadWayne, NJ 07470Copy to:Ronald DaitzWeil, Gotshal & Manges LLP767 Fifth AvenueNew York, NY 10153-0019


Acknowledged
and Accepted by:  Deutsche
Bank AG New York Branch, as Collateral
Agent   By:
  /Marguerite
  Sutton/Name: Marguerite SuttonTitle: DirectorBy:
  /Enrique
  Landaeta/Name: Enrique LandaetaTitle: Vice President