Exhibit 10.1

FIRST AMENDMENT TO CREDIT AGREEMENT

This FIRST AMENDMENT TO CREDIT AGREEMENT (this “Amendment”) is entered into as
of February 5, 2009, among WESTLAKE CHEMICAL CORPORATION (“Westlake”) and
certain of its domestic subsidiaries listed as Borrowers to the Credit Agreement
described below (collectively, the “Borrowers”), Lenders under the Credit
Agreement, BANK OF AMERICA, N.A., in its capacity as Agent for Lenders under the
Credit Agreement (the “Agent”), and Guarantors under the Credit Agreement.

Reference is made to the Amended and Restated Credit Agreement, dated as of
September 8, 2008 (as amended, modified, and supplemented, the “Credit
Agreement”), among the Borrowers, the Guarantors, the Agent, and Lenders party
thereto. Unless otherwise defined in this Amendment, capitalized terms used
herein shall have the meanings set forth in the Credit Agreement and all Section
references herein are to Sections in the Credit Agreement.

RECITALS

A. The Borrowers have requested that Required Lenders agree to amend certain
provisions of the Credit Agreement, including without limitation, amending the
relevant provisions relating to Distributions and Acquisitions.

B. Subject to the terms and conditions of this Amendment, Required Lenders are
willing to make such amendments.

Accordingly, for adequate and sufficient consideration, the parties hereto agree
as follows:

Paragraph 1. Amendments to Credit Agreement.

1.1. The definition of “2009 Acquisition Basket” is added to Annex A to the
Credit Agreement in the appropriate alphabetic order:

“2009 Acquisition Basket” means $100,000,000.

1.2. The definition of “Acquisition Basket Carryforward” is added to Annex A to
the Credit Agreement in the appropriate alphabetic order:

“Acquisition Basket Carryforward” means, to the extent the entire amount of the
2009 Acquisition Basket is not utilized in Fiscal Year 2009, the difference
between (a) the 2009 Acquisition Basket and (b) the Acquisition Consideration of
all Acquisitions consummated in Fiscal Year 2009 pursuant to Section 7.26
hereof; provided that if such difference exceeds $25,000,000, the Acquisition
Basket Carryforward shall be $25,000,000.

1.3. The definition of “Acquisition Consideration” is added to Annex A to the
Credit Agreement in the appropriate alphabetic order:

“Acquisition Consideration” means, with respect to an Acquisition, the entire
amount of consideration (cash or non-cash, including assumed obligations, all
indemnities, earnouts and other contingent payment obligations) paid by any Loan
Party in connection with such Acquisition; provided that (a) consideration
consisting of Capital Stock of Westlake or cash proceeds from a contemporaneous
Equity Issuance by Westlake (in either case, other than issuance or exchange to
a Loan Party or any Subsidiary thereof) and (b) any prior Investments in the
acquired Person permitted under the Agreement when made, shall not be included
in calculating such Acquisition Consideration.

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1.4. The definition of “Applicable Margin” in Annex A to the Credit Agreement is
amended in its entirety to read as follows:

“Applicable Margin” means,

 

  (i) with respect to Base Rate Loans, (A) from February 5, 2009 to and
including February 28, 2009, 1.50% per annum, and (B) on and from March 1, 2009,
as set forth in the pricing grid below;

 

  (ii) with respect to LIBOR Rate Loans, (A) from February 5, 2009 to and
including February 28, 2009, 3.00% per annum, and (B) on and from March 1, 2009,
as set forth in the pricing grid below; and

 

  (iii) with respect to the Unused Line Fee, (A) 0.875% per annum if the average
Aggregate Revolver Outstandings for the applicable month are less than 50% of
the Total Facility, or (B) 0.75% per annum in all other cases.

 

Average Daily Excess Availability

   Applicable Margin
for LIBOR Rate
Loans     Applicable Margin for Base
Rate Loans  

< $100,000,000

   3.50 %   2.00 %

> $100,000,000 but < $200,000,000

   3.25 %   1.75 %

> $200,000,000 but < $300,000,000

   3.00 %   1.50 %

> $300,000,000

   2.75 %   1.25 %

On and from March 1, 2009, the Applicable Margins for LIBOR Rate Loans and Base
Rate Loans will be adjusted monthly based upon the above pricing grid. The
average daily Availability is calculated monthly and each new Applicable Margin
shall be effective as of the first day of the subsequent month based on the
average daily Availability with respect to the immediately preceding month with
respect to all outstanding Obligations.

1.5. The definition of “Base Rate” in Annex A to the Credit Agreement is amended
in its entirety to read as follows:

“Base Rate” means, for any day, a per annum rate equal to the greatest of
(a) the Prime Rate for such day; (b) the Federal Funds Rate for such day, plus
0.50%; or (c) LIBOR Rate for a 30 day interest period as determined on such day,
plus 1.0%.

1.6. The definition of “Borrowing Base” in Annex A to the Credit Agreement is
amended in its entirety to read as follows:

“Borrowing Base” means, at any time, an amount equal to (a) the sum of
(i) eighty-five percent (85%) of the Net Amount of Eligible Accounts; plus
(ii) the lesser of (y) seventy percent (70%) of the value of the lower of cost
or market of Eligible Inventory or (z) eighty-five percent (85%) of the Net
Orderly Liquidation Value of all Eligible Inventory; plus (iii) one hundred
percent (100%) of cash held in an account maintained at the Bank or its
Affiliates and satisfactory to the Bank, and subject to a control agreement in
form and substance satisfactory to the Agent (the “Eligible Cash”); minus
(b) Reserves from time to time established by the Agent in its reasonable credit
judgment, including Reserves required under the Agreement in connection with any
Permitted Quarterly Distribution; provided that the aggregate Revolving Loans
advanced against Eligible Inventory shall not exceed the Maximum Inventory Loan
Amount.

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1.7. The definition of “Defaulting Lender” in Annex A to the Credit Agreement is
amended in its entirety to read as follows:

“Defaulting Lender” means any Lender that (a) fails to make any payment or
provide funds to the Agent or any Borrower as required hereunder or fails
otherwise to perform its obligations under any Loan Document, and such failure
is not cured within one (1) Business Day, or (b) is not Solvent or is subject to
any bankruptcy, reorganization or similar proceedings.

1.8. The definition of “First Amendment” is added to Annex A to the Credit
Agreement in the appropriate alphabetic order:

“First Amendment” means that certain First Amendment dated as of February 5,
2009, by and among the Borrowers, the Guarantors, the Agent, and Required
Lenders.

1.9. The definition of “Insolvent Lender” in Annex A to the Credit Agreement is
deleted.

1.10. The definition of “Letter of Credit Obligations” is added to Annex A to
the Credit Agreement in the appropriate alphabetic order:

“Letter of Credit Obligations” means the sum (without duplication) of (a) all
amounts owing by the Borrowers for any drawings under Letters of Credit; (b) the
stated amount of all outstanding Letters of Credit; and (c) all fees and other
amounts owing with respect to Letters of Credit.

1.11. The definition of “Permitted Quarterly Distribution” is added to Annex A
to the Credit Agreement in the appropriate alphabetic order:

“Permitted Quarterly Distribution” means the quarterly Distributions made and/or
declared and permitted under Option C of Section 7.10(a)(ii).

1.12. The definition of “Prime Rate” is added to Annex A to the Credit Agreement
in the appropriate alphabetic order:

“Prime Rate” means the rate of interest announced by the Bank from time to time
as its prime rate. Such rate is set by the Bank on the basis of various factors,
including its costs and desired return, general economic conditions and other
factors, and is used as a reference point for pricing some loans, which may be
priced at, above or below such rate. Any change in such rate announced by the
Bank shall take effect at the opening of business on the day specified in the
public announcement of such change.

1.13. The definition of “Prior Permitted Acquisition” is added to Annex A to the
Credit Agreement in the appropriate alphabetic order:

“Prior Permitted Acquisition” means any Acquisition consummated in compliance
with Section 7.26 as existing prior to the effective date of the First
Amendment.

1.14. The definition of “Prior Permitted Distributions” is added to Annex A to
the Credit Agreement in the appropriate alphabetic order:

“Prior Permitted Distributions” means any Distribution made and/or declared and
permitted under Option A of Section 7.10(a)(ii).

1.15. The definition of “Release Conditions” is added to Annex A to the Credit
Agreement in the appropriate alphabetic order:

“Release Conditions” has the meaning set forth in Option C of
Section 7.10(a)(ii).

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1.16. The definition of “Triggering Date” in Annex A to the Credit Agreement is
amended in its entirety to read as follows:

“Triggering Date” means the date upon which Availability is less than
(a) $75,000,000 for at least three (3) consecutive Business Days, or
(b) $65,000,000 at any time; provided that in the event (x) Availability has
been greater than $75,000,000 at all times for ninety (90) consecutive days and
(y) the Adjusted Fixed Charge Coverage Ratio on such date of determination is
not less than 1.0 to 1.0, commencing on the first day of any month after the
criteria set forth above is satisfied, then the Triggering Date shall be deemed
to not be continuing for purposes of this Agreement, and the requirements of
Section 7.21 shall not be required unless a subsequent Triggering Date occurs.

1.17. Section 1.3(c) of the Credit Agreement is amended by (i) deleting the word
“and” at the end of clause (i) thereof, (ii) renumbering clause (ii) thereof as
“(iii)”, and (iii) adding the following clause (ii) immediately after clause
(i):

(ii) If a Defaulting Lender exists, no Letter of Credit Issuer shall have any
obligation to issue any Letter of Credit and the Agent shall not have any
obligation to provide any Credit Support, until such Lender or the Borrowers
have entered into arrangements satisfactory to the Agent and the applicable
Letter of Credit Issuer to eliminate any funding risk associated with the
Defaulting Lender; and

1.18. Section 1.3(g) of the Credit Agreement is amended in its entirety to read
as follows:

(g) Supporting Letter of Credit; Cash Collateral. (i) If, notwithstanding the
provisions of Section 1.3(b) and Section 10.1, any Letter of Credit or Credit
Support is outstanding upon the termination of this Agreement, then upon such
termination the Borrowers shall deposit with the Agent, for the ratable benefit
of the Agent and the Lenders, with respect to each Letter of Credit or Credit
Support then outstanding, a standby letter of credit (a “Supporting Letter of
Credit”) in form and substance satisfactory to the Agent, issued by an issuer
satisfactory to the Agent in an amount equal to the greatest amount for which
such Letter of Credit or such Credit Support may be drawn plus any fees and
expenses associated with such Letter of Credit or such Credit Support, under
which Supporting Letter of Credit the Agent is entitled to draw amounts
necessary to reimburse the Agent and the Lenders for payments to be made by the
Agent and the Lenders under such Letter of Credit or Credit Support and any fees
and expenses associated with such Letter of Credit or Credit Support. Such
Supporting Letter of Credit shall be held by the Agent, for the ratable benefit
of the Agent and the Lenders, as security for, and to provide for the payment
of, the aggregate undrawn amount of such Letters of Credit or such Credit
Support remaining outstanding. In the event Supporting Letters of Credit are not
delivered, then the Loan Parties shall provide cash collateral for all remaining
Letters of Credit in an amount equal to 110% of the aggregate face amount of
such Letters of Credit. (ii) If a Defaulting Lender exists, the Borrowers shall,
on demand by any Letter of Credit Issuer or the Agent from time to time, cash
collateralize the Pro Rata Share of any Defaulting Lender of the Letter of
Credit Obligations.

1.19. Section 7.10(a) of the Credit Agreement is amended in its entirety to read
as follows:

(a) directly or indirectly declare or make, or incur any liability to make, any
Distribution (other than Distributions payable in Capital Stock (other than
Disqualified Stock) of Westlake), except:

(i) Distributions made and/or declared by wholly owned Subsidiaries; and

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(ii)(A) Distributions permitted under Option A, if the Fixed Charge Coverage
Ratio, after giving effect to such Distribution, is at least 1:0:1.0,
(B) Distributions permitted under Option B, if the Fixed Charge Coverage Ratio,
after giving effect to such Distribution, is less than 1:0:1.0, and
(C) Distributions permitted under Option C, if no Distribution may be made
and/or declared under either Option A or Option B.

Option A:

Distributions made and/or declared by Westlake and non-wholly owned
Subsidiaries, if, after giving effect to such Distribution, (A) Availability
equals or exceeds $75,000,000, and (B) the Fixed Charge Coverage Ratio is at
least 1:0:1.0.

Option B:

(i) Distributions made and/or declared by Westlake and non-wholly owned
Subsidiaries in the aggregate of up to $40,000,000 in Fiscal Year 2009; provided
that (A) the sum of (1) the aggregate amount of all Distributions made and/or
declared by Westlake and non-wholly owned Subsidiaries in Fiscal Year 2009 and
(2) the aggregate Acquisition Consideration of all Acquisitions consummated in
Fiscal Year 2009 shall not exceed $125,000,000, and (B) Availability, after
giving effect to such Distribution, is at least $200,000,000.

(ii) Distributions made and/or declared by Westlake and non-wholly owned
Subsidiaries in the aggregate of up to $30,000,000 in Fiscal Year 2010; provided
that (A) the sum of (1) the aggregate amount of all Distributions made and/or
declared by Westlake and non-wholly owned Subsidiaries in Fiscal Year 2010 and
(2) the aggregate Acquisition Consideration of all Acquisitions consummated in
Fiscal Year 2010 shall not exceed the sum of (I) $175,000,000 and (II) the
Acquisition Basket Carryforward, and (B) Availability, after giving effect to
such Distribution, is at least $200,000,000.

(iii) Distributions made and/or declared by Westlake and non-wholly owned
Subsidiaries in the aggregate of up to $30,000,000 in each Fiscal Year from
January 1, 2011 to December 31, 2013; provided that (A) the sum of (1) the
aggregate amount of all Distributions made and/or declared by Westlake and
non-wholly owned Subsidiaries in each such Fiscal Year and (2) the aggregate
Acquisition Consideration of all Acquisitions consummated in the same Fiscal
Year shall not exceed $140,000,000, and (B) Availability, after giving effect to
such Distribution, is at least $200,000,000.

For purposes of calculating the amount of Distributions in connection with the
foregoing (i), (ii), and (iii), any Prior Permitted Distribution made and/or
declared during the applicable period shall be excluded, but any Permitted
Quarterly Distribution made during the applicable period shall be included; and
for purposes of calculating the aggregate Acquisition Consideration, any Prior
Permitted Acquisition consummated during the applicable period shall be
excluded.

Option C:

In each fiscal quarter, Distributions made and/or declared by Westlake and
non-wholly owned Subsidiaries of up to $4,500,000 (excluding any Prior Permitted
Distribution and any Distribution made and/or declared under

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Option B in such fiscal quarter); provided that (A) Availability, after giving
effect to such Distribution, is at least $125,000,000, (B) the aggregate amount
of all Distributions made and/or declared by Westlake and non-wholly owned
Subsidiaries under Option B and those under this Option C in the applicable
Fiscal Year shall not exceed $30,000,000 (or $40,000,000 with respect to Fiscal
Year 2009), and (C) the aggregate amount of annual Distributions permitted under
this Option C is reserved from the Borrowing Base until either (x) (1) the Fixed
Charge Coverage Ratio is at least 1.0:1.0 and (2) Availability is at least
$75,000,000, or (y) Availability is at least $200,000,000 (the “Release
Conditions”). In the event (I) a Distribution is made and/or declared under this
Option C, (II) the Release Conditions have been met, and (III) the Release
Conditions cease to be met, then the aggregate amount of annual Distributions
permitted under this Option C will be reserved from the Borrowing Base until the
Release Conditions are met again; provided that (x) Availability shall be
calculated after giving effect to each Distribution made or declared, and
(y) with respect to the Release Conditions, Availability shall be calculated
after giving effect to the Reserves in connection with any Permitted Quarterly
Distribution.

provided that for purposes of a Distribution, Availability shall be calculated
based on the most recent Borrowing Base Certificate delivered pursuant to this
Agreement prior to such Distribution (provided that the amount of Eligible Cash
shall be the amount on deposit on the date of such Distribution and provided
further that the Aggregate Revolver Outstandings shall be calculated on the date
of such Distribution) and Distributions are permitted hereunder only if no
Default or Event of Default then exists and only to the extent that any such
Distribution is made and/or declared in accordance with applicable Requirement
of Law and constitutes a valid, non-voidable transaction.

1.20. Section 7.14(b)(iv) of the Credit Agreement is amended in its entirety to
read as follows:

(iv) so long as no Default or Event of Default has occurred and is continuing
after giving effect to such redemption, defeasance or prepayment, if, after
giving effect to such redemption, defeasance or prepayment, (A) Availability
equals or exceeds $75,000,000, and (B) the Fixed Charge Coverage Ratio is at
least 1:0:1.0; provided that for purposes of this Section 7.14(b)(iv),
Availability shall be calculated based on the most recent Borrowing Base
Certificate delivered pursuant to this Agreement prior to such redemption,
defeasance, or prepayment (provided that the amount of Eligible Cash shall be
the amount on deposit on the date of such redemption, defeasance, or prepayment,
and provided further that the Aggregate Revolver Outstandings shall be
calculated on the date of such redemption, defeasance, or prepayment;

1.21. Section 7.14(c)(ii) of the Credit Agreement is amended in its entirety to
read as follows:

(ii) so long as no Default or Event of Default has occurred and is continuing
after giving effect to such prepayment, redemption, or defeasance, redemptions,
defeasance, or prepayments (whether voluntary or mandatory) (“Bond Debt
Prepayment”) of the Bond Debt, if, after giving effect to such Bond Debt
Prepayment, (A) Availability equals or exceeds $75,000,000, and (B) the Fixed
Charge Coverage Ratio is at least 1:0:1.0; provided that for purposes of this
Section 7.14(c)(ii), Availability shall be calculated based on the most recent
Borrowing Base Certificate delivered pursuant to this Agreement prior to such
Bond Debt Prepayment (provided that the amount of Eligible Cash shall be the
amount on deposit on the date of such Bond Debt Prepayment, and provided further
that the Aggregate Revolver Outstandings shall be calculated on the date of such
Bond Debt Prepayment);

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1.22. Section 7.26(j) of the Credit Agreement is amended in its entirety to read
as follows:

(j) immediately after giving effect to any Acquisition, including any Revolving
Loans to be made in connection with any Acquisition, (i) Availability equals or
exceeds $75,000,000, and (ii) the Pro Forma Fixed Charge Coverage Ratio is at
least 1:0:1.0; and

1.23. Section 7.26 to the Credit Agreement is amended by adding the following
immediately after clause (k) (as separate paragraphs):

provided that with respect to clause (j) above, if the Pro Forma Fixed Charge
Coverage Raito, after giving effect to any Acquisition, including any Revolving
Loans to be made in connection with any Acquisition, is less than 1.0:1.0, Loan
Parties may consummate Acquisitions so long as all the requirements set forth in
(1) the above clauses of this Section 7.26 (other than clause (j)) and (2) the
following are met:

(i) Loan Parties may consummate Acquisitions to the extent the aggregate
Acquisition Consideration of all such Acquisitions do not exceed $100,000,000 in
Fiscal Year 2009; provided that (A) the sum of (1) the aggregate amount of all
Distributions made and/or declared by Westlake and non-wholly owned Subsidiaries
in Fiscal Year 2009 and (2) the aggregate Acquisition Consideration of all
Acquisitions consummated in Fiscal Year 2009 shall not exceed $125,000,000, and
(B) Availability, immediately after giving effect to any Acquisition, including
any Revolving Loans to be made in connection with such Acquisition, is at least
$200,000,000.

(ii) Loan Parties may consummate Acquisitions to the extent the aggregate
Acquisition Consideration of all such Acquisitions do not exceed the sum of
(A) $150,000,000 and (B) the Acquisition Basket Carryforward in Fiscal Year
2010; provided that (A) the sum of (1) the aggregate amount of all Distributions
made and/or declared by Westlake and non-wholly owned Subsidiaries in Fiscal
Year 2010 and (2) the aggregate Acquisition Consideration of all Acquisitions
consummated in Fiscal Year 2010 shall not exceed the sum of (I) $175,000,000 and
(II) the Acquisition Basket Carryforward, and (B) Availability, immediately
after giving effect to any Acquisition, including any Revolving Loans to be made
in connection with such Acquisition, is at least $200,000,000.

(iii) Loan Parties may consummate Acquisitions to the extent the aggregate
Acquisition Consideration of all such Acquisitions do not exceed $125,000,000 in
each Fiscal Year from January 1, 2011 to December 31, 2013; provided that
(A) the sum of (1) the aggregate amount of all Distributions made and/or
declared by Westlake and non-wholly owned Subsidiaries in each such Fiscal Year
and (2) the aggregate Acquisition Consideration of all Acquisitions consummated
in the same Fiscal Year shall not exceed $140,000,000, and (B) Availability,
immediately after giving effect to any Acquisition, including any Revolving
Loans to be made in connection with such Acquisition, is at least $200,000,000.

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For purposes of calculating the amount of Distributions in connection with the
foregoing (i), (ii), and (iii), any Prior Permitted Distribution made and/or
declared during the applicable period shall be excluded, but any Permitted
Quarterly Distribution made and/or declared during the applicable period shall
be included; and for purposes of calculating the aggregate Acquisition
Consideration, any Prior Permitted Acquisition consummated during the applicable
period shall be excluded.

Additionally, for purposes of calculating Availability in connection with the
foregoing Sections 7.26(j) and (k), Availability shall be calculated based on
the most recent Borrowing Base Certificate delivered pursuant to this Agreement
prior to such Acquisition (provided that the amount of Eligible Cash shall be
the amount on deposit on the date of such Acquisition and provided further that
the Aggregate Revolver Outstandings shall be calculated on the date of such
Acquisition).

For purposes of Sections 7.26 and 7.10(c) only, (i) a series of investments not
to exceed $200,000,000 in a Joint Venture which will own a chlor-alkali
manufacturing facility as and to the extent disclosed to Lenders in writing
prior to the effective date of the First Amendment, and (ii) investments in
Suzhou Huasu Plastics Co., Ltd. made on or after the effective date of the First
Amendment, shall each be deemed an Acquisition and not a Restricted Investment,
and no assets at any time owned by such Joint Venture or Suzhou Huasu Plastics
Co., Ltd. shall be included in the Borrowing Base.

1.24. Section 12.14(a)(ii) of the Credit Agreement is amended by adding the
following at the end of clause (ii):

If any settlement amount is not transferred to the Agent by any Lender on the
Business Day after demand, the Agent will notify the Borrowers of such Lender’s
failure to transfer and, upon demand by the Agent, the Borrowers shall pay such
amount to the Agent, together with interest thereon for each day elapsed since
the date of the applicable advance, at a rate per annum equal to the Interest
Rate applicable at the time to the Revolving Loans comprising that particular
advance.

1.25. Section 12.14(c) of the Credit Agreement is amended by deleting the
parenthetical therein.

1.26. Section 12.14(d) of the Credit Agreement is amended in its entirety to
read as follows:

(d) Retention of Defaulting Lender’s Payments. The Agent shall not be obligated
to transfer to a Defaulting Lender any payments made by any Borrower to the
Agent for the Defaulting Lender’s benefit; nor shall a Defaulting Lender be
entitled to the sharing of any payments hereunder, or any interest on the
amounts so held by the Agent. Amounts payable to a Defaulting Lender shall
instead be paid to or retained by the Agent. In its discretion, the Agent may
loan the Borrowers the amount of all such payments received or retained by it
for the account of such Defaulting Lender. Any amounts so loaned to the
Borrowers shall bear interest at the rate applicable to Base Rate Loans and for
all other purposes of this Agreement shall be treated as if they were Revolving
Loans, provided, however, that for purposes of voting or consenting to matters

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with respect to the Loan Documents and determining Pro Rata Shares, such
Defaulting Lender shall be deemed not to be a “Lender”. Until all of the
defaulted obligations of a Defaulting Lender have been cured, (i) such
Defaulting Lender shall not be entitled to any portion of the Unused Line Fee
and the Unused Line Fee shall accrue in favor of the Lenders which have funded
their respective Pro Rata Shares of such requested Borrowing and shall be
allocated among such performing Lenders ratably based upon their relative
Commitments; and (ii) such Defaulting Lender shall not be entitled to any
portion of the proceeds from any Collateral. This Section shall remain effective
with respect to such Lender until such time as the Defaulting Lender shall no
longer be in default of any of its obligations under this Agreement. The terms
of this Section shall not be construed to increase or otherwise affect the
Commitment of any Lender, or relieve or excuse the performance by the Borrowers
of their duties and obligations hereunder.

1.27. Section 12.14(e) of the Credit Agreement is amended in its entirety to
read as follows:

(e) Removal of Defaulting Lender. At the Borrowers’ request and to the extent
permitted by applicable law, the Agent or an Eligible Assignee reasonably
acceptable to the Agent shall have the right (but not the obligation) to
purchase from any Defaulting Lender, and each Defaulting Lender shall, upon such
request, sell and assign to the Agent or such Eligible Assignee, all of such
Lender’s outstanding Commitment hereunder. Such sale shall be consummated
promptly after the Agent has arranged for a purchase by the Agent or an Eligible
Assignee pursuant to an Assignment and Acceptance, and at a price equal to the
outstanding principal balance of such Lender’s Revolving Loans, plus accrued
interest and fees, without premium or discount. To the extent permitted by
applicable law, the Agent is irrevocably appointed as attorney-in-fact of such
Defaulting Lender to execute any such Assignment and Acceptance if such Lender
fails to execute same within twenty (20) days of such request of assignment.

Paragraph 2. Effective Date. Notwithstanding any contrary provision, this
Amendment is not effective until the date (the “Effective Date”) upon which:

2.1. the Agent has received counterparts of this Amendment executed by each
Borrower, each Guarantor, the Agent, and the Required Lenders;

2.2. the Agent has received such opinions of in-house counsel for the Loan
Parties in form, scope, and substance reasonably satisfactory to the Agent;

2.3. the Agent has received duly executed Officers’ Certificates and resolutions
evidencing the authorization of this Amendment and the transactions contemplated
hereby;

2.4. all representations and warranties made hereunder and in the other Loan
Documents shall be true and correct as of the date hereof as though made on and
as of the date hereof, except to the extent that (i) any of them speak to a
different specific date or (ii) the facts on which any of them were based have
been changed by transactions contemplated or permitted by the Credit Agreement;

2.5. after giving effect to this Amendment, no Default or Event of Default shall
have occurred and be continuing;

2.6. the Borrowers shall have paid each Lender that has consented to and
executed this Amendment on or prior to the Effective Date an amendment fee equal
to 0.20% of such Lender’s Commitment as set forth on Schedule 1.2 to the Credit
Agreement; such fees, once paid, shall be fully earned and nonrefundable for any
reason whatsoever;

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2.7. the Borrowers shall have paid Attorney Costs of the Agent incurred in
connection with the Loan Documents, including any outstanding Attorney Costs of
the Agent on or prior to the Effective Date; and

2.8. the Borrowers shall have paid all other fees due and payable on or prior to
the Effective Date, including without limitation, the fees set forth in the Fee
Letter dated the date hereof between the Agent and Westlake.

Paragraph 3. Acknowledgment and Ratification. As a material inducement to the
Agent and Lenders to execute and deliver this Amendment, each Borrower and each
Guarantor (a) consent to the agreements in this Amendment, and (b) agree and
acknowledge that the execution, delivery, and performance of this Amendment
shall in no way release, diminish, impair, reduce, or otherwise affect the
respective obligations of the Borrowers or the Guarantors under their respective
Loan Documents, which Loan Documents shall remain in full force and effect, and
all Liens, guaranties, and rights thereunder are hereby ratified and confirmed.
The receipt of each Guarantor’s consent and acknowledgement hereunder shall not
constitute a requirement that the Agent and Lenders obtain such consent or
acknowledgement in connection with any other amendment, modification, or waiver
of any term or provision of any Loan Documents.

Paragraph 4. Representations. As a material inducement to Lenders to execute and
deliver this Amendment, each Borrower and each Guarantor represent and warrant
to Lenders (with the knowledge and intent that Lenders are relying upon the same
in entering into this Amendment) that as of the Effective Date and as of the
date of execution of this Amendment, (a) all representations and warranties in
the Loan Documents are true and correct in all material respects as though made
on the date hereof, except to the extent that (i) any of them speak to a
different specific date or (ii) the facts on which any of them were based have
been changed by transactions contemplated or permitted by the Credit Agreement,
(b) no Default or Event of Default exists, (c) the attachments to, and the
certifications made in, the Officer’s Certificates most recently executed and
delivered to the Agent and Lenders by each Borrower and Guarantor, have not been
modified or amended, remain in full force and effect, and are hereby ratified
and confirmed, and (d) the execution, delivery, and performance of this
Amendment have been duly authorized by all necessary partnership, limited
liability company, and corporate action and this Amendment constitutes the valid
and binding obligation of each of them.

Paragraph 5. Fees and Expenses. The Borrowers shall pay all reasonable costs,
fees, and expenses paid or incurred by the Agent in connection with this
Amendment, including, without limitation, Attorney Costs of the Agent in
connection with the negotiation, preparation, delivery, and execution of this
Amendment and any related documents.

Paragraph 6. Waiver. Each Loan Party (a) acknowledges and agrees that, as of the
date hereof, it has no actual or potential claim or cause of action against the
Agent or any Lender relating to any Loan Documents or any actions or events
occurring on or before the date of this Amendment and (b) waives and releases
any right to assert such claim or cause of action to the extent based on actions
or events occurring on or before the date hereof.

Paragraph 7. Miscellaneous.

7.1. This Amendment is a “Loan Document” referred to in the Credit Agreement,
and the provisions relating to Loan Documents in Article 13 of the Credit
Agreement are incorporated in this Amendment by reference. Unless stated
otherwise (a) the singular number includes the plural and vice versa and words
of any gender include each other gender, in each case, as appropriate,
(b) headings and captions may not be construed in interpreting provisions,
(c) this Amendment must be construed, and its performance enforced, under the
substantive laws of the State of New York, (d) if any part of this Amendment is
for any reason found to be unenforceable, all other portions of it nevertheless
remain enforceable, and (e) this Amendment may be executed in any number of
counterparts with the same effect as if all signatories had signed the same
document, and all of those counterparts must be construed together to constitute
the same document.

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7.2. The Loan Documents shall remain unchanged and in full force and effect,
except as provided in this Amendment, and are hereby ratified and confirmed. On
and after the Effective Date, all references to the “Credit Agreement” shall be
to the Credit Agreement as herein amended. The execution, delivery, and
effectiveness of this Amendment shall not operate as a waiver of any rights of
Lenders under any Loan Document, nor constitute a waiver under any of the Loan
Documents.

Paragraph 8. Entire Agreement. THIS AMENDMENT REPRESENTS THE FINAL AGREEMENT
BETWEEN THE PARTIES ABOUT THE SUBJECT MATTER OF THIS AMENDMENT AND MAY NOT BE
CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL
AGREEMENTS OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE
PARTIES.

Paragraph 9. Parties. This Amendment binds and inures to the Borrowers, the
Guarantors, the Agent, Lenders, and their respective successors and assigns.

The parties hereto have executed this Amendment in multiple counterparts to be
effective as of the Effective Date.

Remainder of Page Intentionally Blank.

Signature Pages to Follow.

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BORROWERS AND GUARANTORS: WESTLAKE CHEMICAL CORPORATION, a Delaware corporation

WESTLAKE PVC CORPORATION,

a Delaware corporation

WESTLAKE VINYLS, INC.,

a Delaware corporation

NORTH AMERICAN BRISTOL CORPORATION, a Delaware corporation WESTLAKE LONGVIEW
CORPORATION, a Delaware corporation WESTLAKE ETHYLENE PIPELINE CORPORATION, a
Delaware corporation WESTLAKE SUPPLY AND TRADING COMPANY, a Delaware corporation
By:  

/s/ Albert Chao

  Albert Chao   President of the above Borrowers

Signature Page to First Amendment to

Westlake A&R Credit Agreement

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NORTH AMERICAN PIPE CORPORATION, a Delaware corporation

VAN BUREN PIPE CORPORATION,

a Delaware corporation

WESTECH BUILDING PRODUCTS, INC.,

a Delaware corporation

WESTECH PROFILES LIMITED,

a Delaware corporation

By:  

/s/ Wayne D. Morse

  Wayne D. Morse   President of the above Borrowers

Signature Page to First Amendment to

Westlake A&R Credit Agreement

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WESTLAKE VINYLS COMPANY LP, a Delaware limited partnership By:   GVGP, Inc., its
general partner By:  

/s/ Albert Chao

  Albert Chao   President of the general partner of the above Borrower

WESTLAKE PETROCHEMICALS LLC,

a Delaware limited liability company

WESTLAKE POLYMERS LLC,

a Delaware limited liability company

WESTLAKE STYRENE LLC,

a Delaware limited liability company

WPT LLC,

a Delaware limited liability company

By:   Westlake Chemical Investments, Inc., its manager By:  

/s/ Albert Chao

  Albert Chao   President of the manager of the above Borrowers

Signature Page to First Amendment to

Westlake A&R Credit Agreement

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GUARANTORS: GEISMAR HOLDINGS, INC., a Delaware corporation WESTLAKE DEVELOPMENT
CORPORATION, a Delaware corporation

GVGP, INC.,

a Delaware corporation

WESTLAKE CHEMICAL INVESTMENTS, INC., a Delaware corporation WESTLAKE MANAGEMENT
SERVICES, INC., a Delaware corporation WESTLAKE OLEFINS CORPORATION, a Delaware
corporation WESTLAKE RESOURCES CORPORATION, a Delaware corporation WESTLAKE
VINYL CORPORATION, a Delaware corporation WESTLAKE NG I CORPORATION, a Delaware
corporation WESTLAKE NG III CORPORATION, a Delaware corporation WESTLAKE NG IV
CORPORATION, a Delaware corporation WESTLAKE NG V CORPORATION, a Delaware
corporation By:  

/s/ Albert Chao

  Albert Chao   President of the above Guarantors

Signature Page to First Amendment to

Westlake A&R Credit Agreement

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BANK OF AMERICA, N.A., as the Agent and a Lender By:  

/s/ David T. Knoblauch

  David T. Knoblauch   Senior Vice President

Signature Page to First Amendment to

Westlake A&R Credit Agreement

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WELLS FARGO FOOTHILL, LLC, as a Lender By:  

/s/ Juan Barrera

Name:   Juan Barrera Title:   Vice President

Signature Page to First Amendment to

Westlake A&R Credit Agreement

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BURDALE CAPITAL FINANCE INC., as a Lender By:  

/s/ Phillip R. Webb

Name:   Phillip R. Webb Title:   Director By:  

/s/ Antimo Barbieri

Name:   Antimo Barbieri Title:   Senior Vice President

Signature Page to First Amendment to

Westlake A&R Credit Agreement

--------------------------------------------------------------------------------

JPMORGAN CHASE BANK, N.A., as a Lender By:  

/s/ Christy West

Name:   Christy West Title:   Vice President

Signature Page to First Amendment to

Westlake A&R Credit Agreement

--------------------------------------------------------------------------------

COMPASS BANK, as a Lender By:  

/s/ Eric E. Ensmann

Name:   Eric E. Ensmann Title:   Senior Vice President

Signature Page to First Amendment to

Westlake A&R Credit Agreement

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DEUTSCHE BANK TRUST COMPANY AMERICAS, as a Lender By:  

/s/ Marguerite Sutton

Name:   Marguerite Sutton Title:   Director By:  

/s/ Enrique Landaeta

Name:   Enrique Landaeta Title:   Vice President

Signature Page to First Amendment to

Westlake A&R Credit Agreement

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CAPITAL ONE LEVERAGE FINANCE CORPORATION, as a Lender By:  

/s/ Ari Kaplan

Name:   Ari Kaplan Title:   Senior Vice President

Signature Page to First Amendment to

Westlake A&R Credit Agreement

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CREDIT SUISSE, CAYMAN ISLANDS BRANCH, as a Lender By:  

/s/ Alain Discust

Name:   Alain Discust Title:   Director By:  

/s/ Christopher Reo Day

Name:   Christopher Reo Day Title:   Associate

Signature Page to First Amendment to

Westlake A&R Credit Agreement

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PNC BANK, NATIONAL ASSOCIATION, as a Lender By:  

/s/ Timothy S. Culver

Name:   Timothy S. Culver Title:   Vice President

Signature Page to First Amendment to

Westlake A&R Credit Agreement

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SIEMENS FINANCIAL SEVICES, INC., as a Lender By:  

/s/ Jim Fuller

Name:   Jim Fuller Title:   Senior Vice President By:  

/s/ Mark Pacillo

Name:   Mark Pacillo Title:   Vice President

Signature Page to First Amendment to

Westlake A&R Credit Agreement