Filed by Bowne Pure Compliance

TABLE OF CONTENTS


ARTICLE I

Definitions

SECTION 1.01. Credit Agreement			1
SECTION 1.02. Other Defined Terms			1

ARTICLE II

Guarantee

SECTION 2.01. Guarantee			2
SECTION 2.02. Guarantee of Payment			2
SECTION 2.03. No Limitations			3
SECTION 2.04. Reinstatement			3
SECTION 2.05. Agreement To Pay; Subrogation			4
SECTION 2.06. Information			4

ARTICLE III

Indemnity, Subrogation and Subordination

SECTION 3.01. Indemnity and Subrogation			4
SECTION 3.02. Contribution and Subrogation			4
SECTION 3.03. Subordination			5

ARTICLE IV

Miscellaneous

SECTION 4.01. Notices			5
SECTION 4.02. Waivers; Amendment			5
SECTION 4.03. Administrative Agent’s Fees and Expenses; Indemnification			6
SECTION 4.04. Successors and Assigns			6
SECTION 4.05. Survival of Agreement			6
SECTION 4.06. Counterparts; Effectiveness; Several Agreement			7
SECTION 4.07. Severability			7
SECTION 4.08. Right of Set-Off			7
SECTION 4.09. Governing Law; Jurisdiction; Consent to Service of Process			8
SECTION 4.10. WAIVER OF JURY TRIAL			8
SECTION 4.11. Headings			9
SECTION 4.12. Guarantee Absolute			9
SECTION 4.13. Termination or Release			9
SECTION 4.14. Additional Subsidiaries			10
SECTION 4.15. Loan Party Representative			10

GUARANTEE AGREEMENT dated as of September 9, 2008 (this “Agreement”), among USG CORPORATION, a Delaware corporation, in its capacity as a Guarantor (in such capacity, the “Parent Borrower”) and in its capacity as the Loan Party Representative (as such term is defined herein), each Subsidiary of the Parent Borrower from time to time party hereto and JPMORGAN CHASE BANK, N.A., as Administrative Agent.

Reference is made to the Credit Agreement dated as of September 9, 2008 (as amended, restated, supplemented or otherwise modified from time to time, the “Credit Agreement”), among the Parent Borrower, the Loan Party Representative, the Subsidiary Borrowers from time to time party thereto, the Lenders from time to time party thereto and JPMorgan Chase Bank, N.A., as Administrative Agent (in such capacity, the “Administrative Agent”). The Lenders have agreed to extend credit to the Borrowers subject to the terms and conditions set forth in the Credit Agreement. The obligations of the Lenders to extend such credit are conditioned upon, among other things, the execution and delivery of this Agreement. The Subsidiaries party hereto are affiliates of the Borrowers, will derive substantial benefits from the extension of credit to the Borrowers pursuant to the Credit Agreement and are willing to execute and deliver this Agreement in order to induce the Lenders to extend such credit. Accordingly, the parties hereto agree as follows:

ARTICLE I

Definitions

SECTION 1.01. Credit Agreement. (a) Capitalized terms used in this Agreement and not otherwise defined herein have the meanings specified in the Credit Agreement.

(b) The rules of construction specified in Section 1.03 of the Credit Agreement also apply to this Agreement.

SECTION 1.02. Other Defined Terms. As used in this Agreement, the following terms have the meanings specified below:

“Claiming Party” has the meaning assigned to such term in Section 3.02.

“Contributing Party” has the meaning assigned to such term in Section 3.02.

“Credit Agreement” has the meaning assigned to such term in the preliminary statement of this Agreement.

“Guaranteed Parties” means (a) the Lenders, (b) the Administrative Agent, (c) the beneficiaries of each indemnification obligation undertaken by any Loan Party under any Loan Document and (d) the permitted successors and assigns of each of the foregoing.

“Guarantors” means (a) the Parent Borrower, (b) the Subsidiaries identified on Schedule I and (c) each other Subsidiary that becomes a party to this Agreement after the Effective Date, provided that no Borrower shall be deemed to be a Guarantor with respect to any of the Secured Obligations of such Borrower (other than the Obligations of such Borrower described in clause (c) of the definition of the term “Obligations”).

“Loan Party Representative” has the meaning assigned to such term in Section 4.15.

“Parent Borrower” has the meaning assigned to such term in the preliminary statement of this Agreement.

ARTICLE II

Guarantee

SECTION 2.01. Guarantee. Each Guarantor unconditionally guarantees, jointly with the other Guarantors and severally, as a primary obligor and not merely as a surety, the due and punctual payment and performance of the Secured Obligations (including the Secured Obligations of any Subsidiary Borrower designated as such on or after the Effective Date). Each of the Guarantors further agrees that the Secured Obligations may be extended or renewed, in whole or in part, without notice to or further assent from it, and that it will remain bound upon its guarantee notwithstanding any extension or renewal of any Secured Obligation. Each of the Guarantors waives presentment to, demand of payment from and protest to the Borrowers or any other Loan Party of any of the Secured Obligations, and also waives notice of acceptance of its guarantee and notice of protest for nonpayment. For purposes of clarity, each of the Guarantors agrees that the Secured Obligations shall include all obligations under the Loan Documents and all obligations associated with any Banking Services, in each case of any Subsidiary Borrower that is designated as such after the Effective Date.

SECTION 2.02. Guarantee of Payment. Each of the Guarantors further agrees that its guarantee hereunder constitutes a guarantee of payment when due and not of collection, and waives any right to require that any resort be had by the Administrative Agent or any other Guaranteed Party to any security held for the payment of the Secured Obligations or to any balance of any deposit account or credit on the books of the Administrative Agent or any other Guaranteed Party in favor of the Borrowers or any other Person.

SECTION 2.03. No Limitations. (a) Except for termination of a Guarantor’s obligations hereunder as expressly provided in Section 4.13, the obligations of each Guarantor hereunder shall not be subject to any reduction, limitation, impairment or termination for any reason, including any claim of waiver, release, surrender, alteration or compromise, and shall not be subject to any defense or set-off, counterclaim, recoupment or termination whatsoever by reason of the invalidity, illegality or unenforceability of the Secured Obligations or otherwise. Without limiting the generality of the foregoing, the obligations of each Guarantor hereunder shall not be discharged or impaired or otherwise affected by (i) the failure of the Administrative Agent or any other Guaranteed Party to assert any claim or demand or to enforce any right or remedy under the provisions of any Loan Document or otherwise; (ii) any rescission, waiver, amendment or modification of, or any release from any of the terms or provisions of, any Loan Document or any other agreement, including with respect to any other Guarantor under this Agreement; (iii) the release of any security, if any, held by the Administrative Agent or any other Guaranteed Party for the Secured Obligations or any of them; (iv) any default, failure or delay, wilful or otherwise, in the performance of the Secured Obligations; or (v) any other act or omission that may or might in any manner or to any extent vary the risk of any Guarantor or otherwise operate as a discharge of any Guarantor as a matter of law or equity (other than the payment in full in cash of all the Secured Obligations).

(b) To the fullest extent permitted by applicable law, each Guarantor waives any defense based on or arising out of any defense of the Parent Borrower or any other Loan Party or the unenforceability of the Secured Obligations or any part thereof from any cause, or the cessation from any cause of the liability of the Parent Borrower or any other Loan Party, other than the payment in full in cash of all the Secured Obligations. The Administrative Agent may, at its election, foreclose on any security held by it by one or more judicial or nonjudicial sales, accept an assignment of any such security in lieu of foreclosure, compromise or adjust any part of the Secured Obligations, make any other accommodation with the Parent Borrower or any other Loan Party or exercise any other right or remedy available to it against the Parent Borrower or any other Loan Party, without affecting or impairing in any way the liability of any Guarantor hereunder except to the extent the Secured Obligations have been paid in full in cash. To the fullest extent permitted by applicable law, each Guarantor waives any defense arising out of any such election even though such election may operate, pursuant to applicable law, to impair or to extinguish any right of reimbursement or subrogation or other right or remedy of such Guarantor against the Parent Borrower or any other Loan Party, as the case may be, or any security.

SECTION 2.04. Reinstatement. Each of the Guarantors agrees that its guarantee hereunder shall continue to be effective or be reinstated, as the case may be, if at any time payment, or any part thereof, of any Obligation is rescinded or must otherwise be restored by the Administrative Agent or any other Guaranteed Party upon the bankruptcy or reorganization of the Parent Borrower, any other Loan Party or otherwise.

SECTION 2.05. Agreement To Pay; Subrogation. In furtherance of the foregoing and not in limitation of any other right that the Administrative Agent or any other Guaranteed Party has at law or in equity against any Guarantor by virtue hereof, upon the failure of the Parent Borrower or any other Loan Party to pay any Secured Obligation when and as the same shall become due, whether at maturity, by acceleration, after notice of prepayment or otherwise, each Guarantor hereby promises to and will forthwith pay, or cause to be paid, to the Administrative Agent for distribution to the applicable Guaranteed Parties in cash the amount of such unpaid Secured Obligation. Upon payment by any Guarantor of any sums to the Administrative Agent as provided above, all rights of such Guarantor against the Parent Borrower or any other Loan Party arising as a result thereof by way of right of subrogation, contribution, reimbursement, indemnity or otherwise shall in all respects be subject to Article III.

SECTION 2.06. Information. Each Guarantor assumes all responsibility for being and keeping itself informed of the Parent Borrower’s and each other Loan Party’s financial condition and assets, and of all other circumstances bearing upon the risk of nonpayment of the Secured Obligations and the nature, scope and extent of the risks that such Guarantor assumes and incurs hereunder, and agrees that none of the Administrative Agent or the other Guaranteed Parties will have any duty to advise such Guarantor of information known to it or any of them regarding such circumstances or risks.

ARTICLE III

Indemnity, Subrogation and Subordination

SECTION 3.01. Indemnity and Subrogation. In addition to all such rights of indemnity and subrogation as the Guarantors may have under applicable law (but subject to Section 3.03), each Guarantor that is a Borrower agrees, in its capacity as a Borrower, that in the event a payment of an obligation of such Guarantor shall be made by any other Guarantor under this Agreement, such Guarantor, in its capacity as a Borrower, shall indemnify such other Guarantor for the full amount of such payment and such other Guarantor shall be subrogated to the rights of the Person to whom such payment shall have been made to the extent of such payment.

SECTION 3.02. Contribution and Subrogation. Each Guarantor (a “Contributing Party”) agrees (subject to Section 3.03) that, in the event a payment shall be made by any other Guarantor hereunder in respect of any Secured Obligation and such other Guarantor (the “Claiming Party”) shall not have been fully indemnified by the applicable Borrower as provided in Section 3.01, the Contributing Party shall indemnify the Claiming Party in an amount equal to the amount of such payment multiplied by a fraction of which the numerator shall be the net worth of the Contributing Party on the date hereof (or, in the case of any Guarantor becoming a party hereto pursuant to Section 4.14, the date of the supplement hereto executed and delivered by such Guarantor) and the denominator shall be the aggregate net worth of all the Guarantors on the date hereof (or, in the case of any Guarantor becoming a party hereto pursuant to Section 4.14, the date of the supplement hereto executed and delivered by such Guarantor). Any Contributing Party making any payment to a Claiming Party pursuant to this Section 3.02 shall be subrogated to the rights of such Claiming Party under Section 3.01 to the extent of such payment.

SECTION 3.03. Subordination. (a) Notwithstanding any provision of this Agreement to the contrary, all rights of the Guarantors under Sections 3.01 and 3.02 and all other rights of indemnity, contribution or subrogation under applicable law or otherwise shall be fully subordinated to the payment in full in cash of the Secured Obligations. No failure on the part of any Borrower or any Guarantor to make the payments required by Sections 3.01 and 3.02 (or any other payments required under applicable law or otherwise) shall in any respect limit the obligations and liabilities of any Guarantor with respect to its obligations hereunder, and each Guarantor shall remain liable for the full amount of the obligations of such Guarantor hereunder.

(b) Each Guarantor hereby agrees that, on and after the Existing Credit Agreement Termination Date, all Indebtedness owed by it to any other Subsidiary that is not a Loan Party shall be fully subordinated to the payment in full in cash of the Secured Obligations.

ARTICLE IV

Miscellaneous

SECTION 4.01. Notices. All communications and notices hereunder shall (except as otherwise expressly permitted herein) be in writing and given as provided in Section 9.01 of the Credit Agreement. All communications and notices hereunder to any Guarantor shall be given to it in care of the Loan Party Representative as provided in Section 9.01 of the Credit Agreement.

SECTION 4.02. Waivers; Amendment. (a) No failure or delay by the Administrative Agent or any Lender in exercising any right or power hereunder or under any other Loan Document shall operate as a waiver thereof, nor shall any single or partial exercise of any such right or power, or any abandonment or discontinuance of steps to enforce such a right or power, preclude any other or further exercise thereof or the exercise of any other right or power. The rights and remedies of the Administrative Agent and the Lenders hereunder and under the other Loan Documents are cumulative and are not exclusive of any rights or remedies that they would otherwise have. No waiver of any provision of this Agreement or consent to any departure by any Guarantor or the Loan Party Representative therefrom shall in any event be effective unless the same shall be permitted by paragraph (b) of this Section 4.02, and then such waiver or consent shall be effective only in the specific instance and for the purpose for which given. Without limiting the generality of the foregoing, the making of a Loan shall not be construed as a waiver of any Default, regardless of whether the Administrative Agent or any Lender may have had notice or knowledge of such Default at the time. No notice or demand on any Guarantor in any case shall entitle any Guarantor to any other or further notice or demand in similar or other circumstances.

(b) Neither this Agreement nor any provision hereof may be waived, amended or modified except pursuant to an agreement or agreements in writing entered into by the Administrative Agent and the Guarantor or Guarantors (or, if applicable, the Loan Party Representative) with respect to which such waiver, amendment or modification is to apply, subject to any consent required in accordance with Section 9.02 of the Credit Agreement.

SECTION 4.03. Administrative Agent’s Fees and Expenses; Indemnification. (a) The parties hereto agree that the Administrative Agent shall be entitled to reimbursement of its expenses incurred hereunder as provided in Section 9.03 of the Credit Agreement.

(b) Without limitation of its indemnification obligations under the other Loan Documents, each Guarantor jointly and severally agrees to indemnify the Administrative Agent and the other Indemnitees (as defined in Section 9.03 of the Credit Agreement) against, and hold each Indemnitee harmless from, any and all out-of-pocket losses, claims, damages, liabilities and related reasonable expenses, including the reasonable fees, charges and disbursements of any counsel for any Indemnitee, incurred by or asserted against any Indemnitee arising out of, in connection with, or as a result of, the execution, delivery or performance of this Agreement or any claim, litigation, investigation or proceeding relating to this Agreement or any instrument contemplated hereby, whether or not any Indemnitee is a party thereto, provided that such indemnity shall not, as to any Indemnitee, be available to the extent that such losses, claims, damages, liabilities or related expenses are determined by a court of competent jurisdiction by final and nonappealable judgment to have resulted from the gross negligence or wilful misconduct of such Indemnitee.

(c) Any such amounts payable as provided hereunder shall be additional Secured Obligations guaranteed hereby. The provisions of this Section 4.03 shall remain operative and in full force and effect regardless of the termination of this Agreement or any other Loan Document, the consummation of the transactions contemplated hereby, the repayment of any of the Secured Obligations, the invalidity or unenforceability of any term or provision of this Agreement or any other Loan Document, or any investigation made by or on behalf of the Administrative Agent or any other Guaranteed Party. All amounts due under this Section 4.03 shall be payable not later than three Business Days after written demand therefor setting forth the basis for such claim in reasonable detail.

SECTION 4.04. Successors and Assigns. Whenever in this Agreement any of the parties hereto is referred to, such reference shall be deemed to include the permitted successors and assigns of such party; and all covenants, promises and agreements by or on behalf of any Guarantor or the Administrative Agent that are contained in this Agreement shall bind and inure to the benefit of their respective successors and assigns.

SECTION 4.05. Survival of Agreement. All covenants, agreements, representations and warranties made by the Loan Party Representative and the Loan Parties in the Loan Documents and in the certificates or other instruments prepared or delivered in connection with or pursuant to this Agreement or any other Loan Document shall be considered to have been relied upon by the Lenders and shall survive the execution and delivery of the Loan Documents and the making of any Loans, regardless of any investigation made by any Lender or on its behalf and notwithstanding that the Administrative Agent or any Lender may have had notice or knowledge of any Default or incorrect representation or warranty at the time any credit is extended under the Credit Agreement, and shall continue in full force and effect as long as the principal of or any accrued interest on any Loan or any fee or any other amount payable under any Loan Document is outstanding and unpaid and so long as the Commitments have not expired or terminated.

SECTION 4.06. Counterparts; Effectiveness; Several Agreement. This Agreement may be executed in counterparts, each of which shall constitute an original but all of which when taken together shall constitute a single contract. Delivery of an executed signature page to this Agreement by facsimile or electronic transmission shall be as effective as delivery of a manually signed counterpart of this Agreement. This Agreement shall become effective as to the Loan Party Representative or any Guarantor when a counterpart hereof executed on behalf of the Loan Party Representative or such Guarantor, as the case may be, shall have been delivered to the Administrative Agent and a counterpart hereof shall have been executed on behalf of the Administrative Agent, and thereafter shall be binding upon the Loan Party Representative, such Guarantor and the Administrative Agent and their respective permitted successors and assigns, and shall inure to the benefit of the Loan Party Representative, such Guarantor, the Administrative Agent and the other Guaranteed Parties and their respective successors and assigns, except that neither the Loan Party Representative nor any Guarantor shall have the right to assign or transfer its rights or obligations hereunder or any interest herein (and any such assignment or transfer shall be void) except as expressly contemplated by this Agreement or the Credit Agreement. This Agreement shall be construed as a separate agreement with respect to each of the Loan Party Representative and each Guarantor and may be amended, modified, supplemented, waived or released with respect to the Loan Party Representative or any Guarantor without the approval of the Loan Party Representative or any other Guarantor, as the case may be, and without affecting the obligations of the Loan Party Representative or any other Guarantor as the case may be, hereunder.

SECTION 4.07. Severability. Any provision of this Agreement held to be invalid, illegal or unenforceable in any jurisdiction shall, as to such jurisdiction, be ineffective to the extent of such invalidity, illegality or unenforceability without affecting the validity, legality and enforceability of the remaining provisions hereof; and the invalidity of a particular provision in a particular jurisdiction shall not invalidate such provision in any other jurisdiction. The parties shall endeavor in good-faith negotiations to replace the invalid, illegal or unenforceable provisions with valid provisions the economic effect of which comes as close as possible to that of the invalid, illegal or unenforceable provisions.

SECTION 4.08. Right of Set-Off. If an Event of Default shall have occurred and be continuing, each Lender and each of its Affiliates is hereby authorized at any time and from time to time, to the fullest extent permitted by law, to set off and apply any and all deposits (general or special, time or demand, provisional or final) at any time held and other obligations at any time owing by such Lender or Affiliate to or for the credit or the account of any Guarantor against any of and all the obligations of such Guarantor now or hereafter existing under this Agreement owed to such Lender, irrespective of whether or not such Lender shall have made any demand under this Agreement and although such obligations may be unmatured. The rights of each Lender under this Section 4.08 are in addition to other rights and remedies (including other rights of set-off) which such Lender may have.

SECTION 4.09. Governing Law; Jurisdiction; Consent to Service of Process. (a) This Agreement shall be construed in accordance with and governed by the law of the State of New York.

(b) Each of the parties hereto hereby irrevocably and unconditionally submits, for itself and its property, to the exclusive jurisdiction of the Supreme Court of the State of New York sitting in New York County and of the United States District Court of the Southern District of New York, and any appellate court from any thereof, in any action or proceeding arising out of or relating to this Agreement or any other Loan Document, or for recognition or enforcement of any judgment, and each of the parties hereto hereby irrevocably and unconditionally agrees that all claims in respect of any such action or proceeding may be heard and determined in such New York State or, to the extent permitted by law, in such Federal court. Each of the parties hereto agrees that a final judgment in any such action or proceeding shall be conclusive and may be enforced in other jurisdictions by suit on the judgment or in any other manner provided by law.

(c) Each of the parties hereto hereby irrevocably and unconditionally waives, to the fullest extent it may legally and effectively do so, any objection which it may now or hereafter have to the laying of venue of any suit, action or proceeding arising out of or relating to this Agreement or any other Loan Document in any court referred to in paragraph (b) of this Section 4.09. Each of the parties hereto hereby irrevocably waives, to the fullest extent permitted by law, the defense of an inconvenient forum to the maintenance of such action or proceeding in any such court.

(d) Each party to this Agreement irrevocably consents to service of process in the manner provided for notices in Section 4.01. Nothing in this Agreement or any other Loan Document will affect the right of any party to this Agreement to serve process in any other manner permitted by law.

SECTION 4.10. WAIVER OF JURY TRIAL. EACH PARTY HERETO HEREBY WAIVES, TO THE FULLEST EXTENT PERMITTED BY APPLICABLE LAW, ANY RIGHT IT MAY HAVE TO A TRIAL BY JURY IN ANY LEGAL PROCEEDING DIRECTLY OR INDIRECTLY ARISING OUT OF OR RELATING TO THIS AGREEMENT, ANY OTHER LOAN DOCUMENT OR THE TRANSACTIONS CONTEMPLATED HEREBY (WHETHER BASED ON CONTRACT, TORT OR ANY OTHER THEORY). EACH PARTY HERETO (A) CERTIFIES THAT NO REPRESENTATIVE, AGENT OR ATTORNEY OF ANY OTHER PARTY HAS REPRESENTED, EXPRESSLY OR OTHERWISE, THAT SUCH OTHER PARTY WOULD NOT, IN THE EVENT OF LITIGATION, SEEK TO ENFORCE THE FOREGOING WAIVER AND (B) ACKNOWLEDGES THAT IT AND THE OTHER PARTIES HERETO HAVE BEEN INDUCED TO ENTER INTO THIS AGREEMENT BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS AND CERTIFICATIONS IN THIS SECTION 4.10.

SECTION 4.11. Headings. Article and Section headings and the Table of Contents used herein are for convenience of reference only, are not part of this Agreement and are not to affect the construction of, or to be taken into consideration in interpreting, this Agreement.

SECTION 4.12. Guarantee Absolute. All rights of the Administrative Agent hereunder and all obligations of each Guarantor hereunder shall be absolute and unconditional irrespective of (a) any lack of validity or enforceability of the Credit Agreement, any other Loan Document, any agreement or instrument governing or evidencing any of the Secured Obligations or any other agreement or instrument relating to any of the foregoing, (b) any change in the time, manner or place of payment of, or in any other term of, all or any of the Secured Obligations, or any other amendment or waiver of or any consent to any departure from the Credit Agreement, any other Loan Document or any other agreement or instrument governing or evidencing any Secured Obligations, (c) any release or amendment or waiver of or consent under or departure from any guarantee guaranteeing all or any of the Secured Obligations, or (d) any other circumstance that might otherwise constitute a defense available to, or a discharge of, any Guarantor in respect of the Secured Obligations or this Agreement (other than the payment in full, in cash, of the Secured Obligations).

SECTION 4.13. Termination or Release. (a) This Agreement and the Guarantees made herein shall terminate when all the Obligations (as distinguished from the Secured Obligations) have been paid in full, in cash, and the Lenders have no further commitment to lend under the Credit Agreement.

(b) A Guarantor shall automatically be released from its obligations hereunder upon the consummation of any transaction permitted by, or that would not otherwise result in a Default under, the Credit Agreement as a result of which such Guarantor ceases to be a Domestic Material Subsidiary, provided that the Required Lenders shall have consented to such transaction (to the extent required by the Credit Agreement) and the terms of such consent did not provide otherwise.

(c) In connection with any termination or release pursuant to paragraph (a) or (b) of this Section 4.13, the Administrative Agent shall execute and deliver to any Guarantor, at such Guarantor’s expense, all documents that such Guarantor shall reasonably request to evidence such termination or release. Any execution and delivery of documents pursuant to this Section 4.13 shall be without recourse to or warranty by the Administrative Agent.

SECTION 4.14. Additional Subsidiaries. Pursuant to Section 5.10(a) of the Credit Agreement, certain Domestic Material Subsidiaries that were not in existence or not Domestic Material Subsidiaries on the date of the Credit Agreement are required to enter in this Agreement as a Guarantor upon becoming such a Domestic Material Subsidiary. Upon execution and delivery by the Administrative Agent and a Subsidiary of an instrument in the form of Exhibit I hereto, such Subsidiary shall become a Guarantor hereunder with the same force and effect as if originally named as a Guarantor herein. The execution and delivery of any such instrument shall not require the consent of any other Guarantor. The rights and obligations of the Loan Party Representative and each Guarantor hereunder shall remain in full force and effect notwithstanding the addition of any new Guarantor as a party to this Agreement.

SECTION 4.15. Loan Party Representative. In addition to the powers granted by any Guarantor in its capacity as a Borrower to the Loan Party Representative under Section 9.17 of the Credit Agreement, each Guarantor hereby designates the Parent Borrower as its representative, agent and attorney-in-fact to act on its behalf (in such capacity, the “Loan Party Representative”) as specified herein or in any other Loan Document. Each Guarantor hereby authorizes the Loan Party Representative to take such actions on its behalf under the terms of this Agreement and the other Loan Documents and to exercise such powers and perform such duties hereunder and thereunder as are specified in such agreements or are reasonably incidental thereto, in each case, on behalf of the Loan Parties under the Loan Documents. The Loan Party Representative hereby accepts such appointment. The Administrative Agent and the Lenders shall be entitled to rely on all notices, requests, consents, certifications and/or authorizations or other similar acts delivered or taken by the Loan Party Representative for or on behalf of any Guarantor pursuant hereto or the other Loan Documents without inquiry and as if such notices, requests, consents, certifications and/or authorizations or other similar acts were delivered by such Guarantor. Each representation, warranty, covenant, agreement and undertaking made on behalf of any Guarantor by the Loan Party Representative shall be deemed for all purposes to have been made by all Guarantors (or any of the them, as applicable) and shall be binding upon and enforceable against such Guarantor to the same extent as it if the same had been made directly by such Guarantor. To the extent that any successor Loan Party Representative is appointed pursuant to Section 9.17 of the Credit Agreement, the Guarantors hereby agree that such Person thereafter shall be vested with all rights, powers, privileges and authority of the Loan Party Representative hereunder without any further action by any Person.

[Signature Pages Follow]

Exhibit I to the
Guarantee Agreement

SUPPLEMENT NO. _____ dated as of _____, 20 _____ (this “Supplement”), to the Guarantee Agreement dated as of September 9, 2008 (as amended, supplemented or otherwise modified from time to time, the “Guarantee Agreement”), among USG CORPORATION, a Delaware corporation, in its capacity as a Guarantor (in such capacity, the “Parent Borrower”) and in its capacity as the Loan Party Representative, the Subsidiaries of the Parent Borrower from time to time party thereto (together with the Parent Borrower, the “Guarantors”) and JPMORGAN CHASE BANK, N.A. (“JPMCB”), as Administrative Agent (in such capacity, the “Administrative Agent”).

A. Reference is made to the Credit Agreement dated as of September 9, 2008 (as amended, supplemented or otherwise modified from time to time, the “Credit Agreement”), among the Parent Borrower, the Loan Party Representative, the Subsidiary Borrowers from time to time party thereto, the Lenders from time to time party thereto and the Administrative Agent.

B. Capitalized terms used herein and not otherwise defined herein shall have the meanings assigned to such terms in the Credit Agreement and the Guarantee Agreement referred to therein.

C. The Guarantors have entered into the Guarantee Agreement in order to induce the Lenders to make Loans. Section 4.14 of the Guarantee Agreement provides that additional Domestic Material Subsidiaries may become Guarantors under the Guarantee Agreement by execution and delivery of an instrument in the form of this Supplement. The undersigned Domestic Material Subsidiary (the “New Subsidiary”) is executing this Supplement in accordance with the requirements of the Credit Agreement to become a Guarantor under the Guarantee Agreement in order to induce the Lenders to make additional Loans and as consideration for Loans previously made.

Accordingly, the Administrative Agent and the New Subsidiary agree as follows:

SECTION 1. In accordance with Section 4.14 of the Guarantee Agreement, the New Subsidiary by its signature below becomes a Guarantor under the Guarantee Agreement with the same force and effect as if originally named therein as a Guarantor and the New Subsidiary hereby (a) agrees to all the terms and provisions of the Guarantee Agreement applicable to it as a Guarantor thereunder, (b) represents and warrants that the representations and warranties made by it as a Guarantor thereunder are true and correct on and as of the date hereof and (c) hereby designates the Person currently acting as Loan Party Representative pursuant to Section 4.15 of the Guarantee Agreement as its representative, agent and attorney-in-fact for all purposes set forth in such Section 4.15. Each reference to a “Guarantor” in the Guarantee Agreement shall be deemed to include the New Subsidiary. The Guarantee Agreement is hereby incorporated herein by reference.

SECTION 2. The New Subsidiary represents and warrants to the Administrative Agent and the other Guaranteed Parties that this Supplement has been duly authorized, executed and delivered by it and constitutes its legal, valid and binding obligation, enforceable against it in accordance with its terms.

SECTION 3. This Supplement may be executed in counterparts (and by different parties hereto on different counterparts), each of which shall constitute an original, but all of which when taken together shall constitute a single contract. This Supplement shall become effective when the Administrative Agent shall have received a counterpart of this Supplement that bears the signature of the New Subsidiary and the Administrative Agent has executed a counterpart hereof. Delivery of an executed signature page to this Supplement by facsimile or electronic transmission shall be as effective as delivery of a manually signed counterpart of this Supplement.

SECTION 4. Except as expressly supplemented hereby, the Guarantee Agreement shall remain in full force and effect.

SECTION 5. THIS SUPPLEMENT SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

SECTION 6. In case any one or more of the provisions contained in this Supplement should be held invalid, illegal or unenforceable in any respect, the validity, legality and enforceability of the remaining provisions contained herein and in the Guarantee Agreement shall not in any way be affected or impaired thereby (it being understood that the invalidity of a particular provision in a particular jurisdiction shall not in and of itself affect the validity of such provision in any other jurisdiction). The parties hereto shall endeavor in good-faith negotiations to replace the invalid, illegal or unenforceable provisions with valid provisions the economic effect of which comes as close as possible to that of the invalid, illegal or unenforceable provisions.

SECTION 7. All communications and notices hereunder shall be in writing and given as provided in Section 4.01 of the Guarantee Agreement.

SECTION 8. The New Subsidiary agrees to reimburse the Administrative Agent for its reasonable out-of-pocket expenses in connection with this Supplement, including the reasonable fees, other charges and disbursements of counsel for the Administrative Agent.

[Signature Pages Follow]



Schedules

Schedule I Subsidiary Guarantors

Exhibits

Exhibit I Form of New Subsidiary Supplement


USG CORPORATION, as a Guarantor Borrower and Loan Party Representative,
by	/s/ Karen L. Leets
	Name:	Karen L. Leets
	Title:	Vice President and Treasurer


EACH OF THE SUBSIDIARIES LISTED ON SCHEDULE I HERETO,
by	/s/ Karen L. Leets
	Name:	Karen L. Leets
	Title:	In the capacity listed on Schedule I corresponding to such Subsidiary


JPMORGAN CHASE BANK, N.A., as the Administrative Agent,
by	/s/ Peter S. Predun
	Name:	Peter S. Predun
	Title:	Executive Director


		Title of Karen L. Leets with respect
Company		to such Company
California Wholesale Material Supply, LLC		Vice President and Treasurer
L&W Supply Corporation		Vice President and Treasurer
Livonia Building Materials, LLC		Vice President and Treasurer
Livonia Holdings, Inc.		Vice President and Treasurer
River City Materials, Inc.		Vice President and Treasurer
United States Gypsum Company		Vice President and Treasurer
USG Foreign Investments, Ltd.		Vice President and Treasurer
USG Interiors, Inc.		Vice President and Treasurer


	JPMORGAN CHASE BANK, N.A., as Administrative Agent,
	by
		Name:
		Title:


Acknowledged and accepted as of the date first written above by:
[NAME OF LOAN PARTY REPRESENTATIVE], as Loan Party Representative,
by:
	Name:
	Title: