WESTLAKE CHEMICAL CORP
SIXTH AMENDMENT TO CREDIT AGREEMENT
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<DESCRIPTION>SIXTH AMENDMENT TO CREDIT AGREEMENT
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 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="right"><FONT FACE="Times New Roman" SIZE="2"><B>Exhibit 10.4 </B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px" ALIGN="right"><FONT
FACE="Times New Roman" SIZE="2">REVOLVER CREDIT AGREEMENT </FONT></P> <P STYLE="margin-top:18px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><U>SIXTH AMENDMENT TO CREDIT AGREEMENT </U></B></FONT></P> <P
STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">This SIXTH AMENDMENT TO CREDIT AGREEMENT (this &#147;<B><I>Amendment</I></B>&#148;) is entered into as of March&nbsp;<U>&nbsp;&nbsp;&nbsp;&nbsp;</U>,
2006, among <B>WESTLAKE CHEMICAL CORPORATION </B>(&#147;<B><I>Westlake</I></B>&#148;) and certain of its domestic subsidiaries listed as Borrowers to the Credit Agreement described below (collectively, the &#147;<B><I>Borrowers</I></B>&#148;),
Lenders under the Credit Agreement, <B>BANK OF AMERICA, N.A.,</B> in its capacity as Agent for Lenders under the Credit Agreement (the &#147;<B><I>Agent</I></B>&#148;), and Guarantors under the Credit Agreement (hereinafter defined). </FONT></P> <P
STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">Reference is made to the Credit Agreement, dated as of July&nbsp;31, 2003 (as amended, modified, and supplemented, the &#147;<B><I>Credit
Agreement</I></B>&#148;), among the Borrowers, 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. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><U>RECITALS </U></FONT></P> <P
STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">A. Borrowers have requested that Lenders agree to amend certain provisions of the Credit Agreement, including without limitation, amending certain
covenants and increasing the Maximum Inventory Loan Amount. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">B. Subject to the terms and conditions of this Amendment, Lenders are willing
to agree to such amendments. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">Accordingly, for adequate and sufficient consideration, the parties hereto agree, as follows: </FONT></P> <P
STYLE="margin-top:6px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B><I>Paragraph 1. <U>Amendments to Credit Agreement</U></I></B>. By execution of this Amendment, the Credit Agreement is hereby amended as follows: </FONT></P> <P
STYLE="margin-top:6px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B>1.1&nbsp;</B><B><I>December Financial Reports</I></B>. The first sentence of <B><I>Section&nbsp;5.2(c)</I></B> of the Credit Agreement is amended in its entirety to
read as follows: </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:8%"><FONT FACE="Times New Roman" SIZE="2">&#147;(c) As soon as available, but in any event not later than thirty (30)&nbsp;days after the end of each month other
than March, June, September, or December (and, as soon as available, but in any event not later than forty-five (45)&nbsp;days after the end of each March, June, and September, and, as soon as available, but in any event not later than the earlier
of (i)&nbsp;the filing of Financial Statements with the SEC pursuant to <B><I>Section&nbsp;5.2(a)</I></B> and (ii)&nbsp;ninety (90)&nbsp;days after the end of each December, and without duplication of the Financial Statements required by
<B><I>Section&nbsp;5.2(b)</I></B>), consolidated unaudited balance sheets of Westlake and its Subsidiaries as at the end of such month, and consolidated unaudited income statements and cash flow statements for Westlake and its Subsidiaries for such
month and for the period from the beginning of the Fiscal Year to the end of such month, all in reasonable detail, fairly presenting the financial position and results of operations of Westlake and its Subsidiaries as at the date thereof and for
such periods, and prepared in accordance with GAAP (except for the inclusion of necessary footnotes) applied consistently with the audited Financial Statements required to be delivered pursuant to <B><I>Section&nbsp;5.2(a)</I></B>, together with a
schedule setting forth in reasonable detail the calculation of the Fixed Charge Coverage Ratio for the immediately preceding twelve (12)&nbsp;month period.&#148; </FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT
SIZE="1">&nbsp;</FONT></P>

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<TD VALIGN="top" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;&nbsp;&nbsp;1&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top" ALIGN="right"><FONT FACE="Times New Roman" SIZE="2"><B>Sixth&nbsp;Amendment&nbsp;to&nbsp;Revolver&nbsp;Credit&nbsp;Agreement</B></FONT></TD></TR>
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 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B>1.2 </B><B><I>Accounts Receivable Reporting</I></B>. <B><I>Section&nbsp;5.2(l)</I></B> of the Credit Agreement is
amended in its entirety to read as follows: </FONT></P> <P STYLE="margin-top:6px;margin-bottom:0px; text-indent:8%"><FONT FACE="Times New Roman" SIZE="2">&#147; (l)&nbsp;As soon as available, but in any event by the second Business Day of each week
for the prior week ending on the last Business Day of such prior week; <I>provided</I> that not more than four (4)&nbsp;times in any fiscal year, the following may be delivered by the third Business Day of such week, in form and substance reasonably
satisfactory to the Agent: (i)&nbsp;a schedule of each Loan Party&#146;s Accounts created, credit memoranda, and collections for the applicable week, <I>together with</I> a reconciliation of each Loan Party&#146;s Accounts created, credit memos,
collections and other adjustments to Accounts since the last such weekly reconciliation and a Borrowing Base Certificate; (ii)&nbsp;a summary of each credit memorandum in excess of $1,000,000; (iii)&nbsp;after the occurrence of the Account
Triggering Date, an Inventory report; and (iv)&nbsp;with the delivery of each of the foregoing, a certificate executed by a Responsible Officer on behalf of all of the Loan Parties certifying as to the accuracy and completeness of the foregoing;
<I>provided that</I> so long as the sum of Availability plus the unrestricted cash of Westlake and its Subsidiaries (A)&nbsp;exceeds $200,000,000 or (B)&nbsp;becomes less than $200,000,000 (during which time the reports and information required to
be delivered pursuant to this <B><I>Section&nbsp;5.2(l)</I></B> shall be delivered on a weekly basis as aforesaid) but thereafter exceeds $250,000,000 for a period of three consecutive months and continues to exceed $200,000,000 after the end of
such three consecutive month period, the reports and other information required to be delivered pursuant to this <B><I>Section&nbsp;5.2(l)</I></B> shall be required to be delivered as soon as available, but in any event within fifteen (15)&nbsp;days
after the end of each month or more frequently as requested by the Agent to determine Availability or otherwise.&#148; </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B>1.3 Maximum Inventory Loan
Amount</B>. The definition of <B><I>Maximum Inventory Loan Amount</I></B> in <B><I>Annex A</I></B> to the Credit Agreement is amended in its entirety to read as follows: </FONT></P> <P STYLE="margin-top:6px;margin-bottom:0px; text-indent:8%"><FONT
FACE="Times New Roman" SIZE="2">"<B><I>&#147;Maximum Inventory Loan Amount&#148;</I></B> means $200,000,000.&#148; </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B><I>Paragraph 2. <U>Amendments to
Security Agreements</U></I></B>. By execution of this Amendment, each of the &#147;$100,000,&#148; &#147;$250,000,&#148; and &#147;$500,000&#148; amounts appearing in <B><I>Sections&nbsp;11(b), (d)</I></B>&nbsp;and <B><I>(e)</I></B>&nbsp;of each of
the Security Agreements is amended to read &#147;$1,000,000.&#148; </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B><I>Paragraph 3. <U>Effective Date</U></I></B>. Notwithstanding any contrary
provision, this Amendment is not effective until the date (the &#147;<B><I>Effective Date</I></B>&#148;) upon which: </FONT></P> <P STYLE="margin-top:6px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">(a) the Agent has
received counterparts of this Amendment executed by each Borrower, each Guarantor, Agent, and each Lender; </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">(b) 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, other than any such representation or warranty which relates to a specified prior date;
</FONT></P> <P STYLE="margin-top:6px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">(c) No Default or Event of Default shall have occurred and be continuing; and </FONT></P> <P
STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">(d) 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 the Effective Date. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B><I>Paragraph 4. <U>Acknowledgment and Ratification</U>. </I></B>As a material inducement to the Agent and Lenders to
execute and deliver this Amendment, each Borrower and each Guarantor (a)&nbsp;consent to the agreements in this Amendment; and (b)&nbsp;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 Borrowers or 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. </FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P>

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<TD VALIGN="top" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;&nbsp;&nbsp;2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top" NOWRAP ALIGN="right"><FONT FACE="Times New Roman" SIZE="2"><B>Sixth&nbsp;Amendment&nbsp;to&nbsp;Revolver&nbsp;Credit Agreement</B></FONT></TD></TR>
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 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B><I>Paragraph 5. <U>Representations</U>.</I></B> 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)&nbsp;all representations and warranties in the Loan Documents are true and correct in all material respects as though made on the date hereof, <I>except</I> to the extent that (i)&nbsp;any of them speak to a different specific date or
(ii)&nbsp;the facts on which any of them were based have been changed by transactions contemplated or permitted by the Credit Agreement, (b)&nbsp;no Default or Event of Default exists, (c)&nbsp;the attachments to, and the certifications made in, the
Officer&#146;s Certificates executed and delivered to the Agent and Lenders in connection with the Fifth Amendment to the Credit Agreement dated as of January&nbsp;6, 2006, have not been modified or amended, remain in full force and effect, and are
hereby ratified and confirmed and (d)&nbsp;the execution, delivery and performance of this Amendment have been duly authorized by all necessary partnership and corporate action and this Amendment constitutes the valid and binding obligation of each
of them. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B><I>Paragraph 6. <U>Fees and Expenses</U></I></B><B></B><B><I>. </I></B>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. </FONT></P> <P
STYLE="margin-top:12px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B><I>Paragraph 7. <U>Waiver</U></I></B>. Each Loan Party (i)&nbsp;acknowledges and agrees that, as of the date hereof, it has no actual or potential claim or cause of
action against Agent or any Lender relating to any Loan Documents or any actions or events occurring on or before the date of this Amendment and (ii)&nbsp;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. </FONT></P> <P STYLE="margin-top:18px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B><I>Paragraph 8. <U>Miscellaneous</U>. </I></B></FONT></P> <P
STYLE="margin-top:6px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">8.1 This Amendment is a <I>&#147;Loan Document&#148;</I> referred to in the Credit Agreement, and the provisions relating to Loan Documents in
<B><I>Article&nbsp;13</I></B> of the Credit Agreement are incorporated in this Amendment by reference. Unless stated otherwise (a)&nbsp;the singular number includes the plural and <I>vice versa</I> and words of any gender include each other gender,
in each case, as appropriate, (b)&nbsp;headings and captions may not be construed in interpreting provisions, (c)&nbsp;this Amendment must be construed, and its performance enforced, under New York law, (d)&nbsp;if any part of this Amendment is for
any reason found to be unenforceable, all other portions of it nevertheless remain enforceable, and (e)&nbsp;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. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">8.2 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 &#147;<I>Credit Agreement&#148;</I> shall be to the Credit Agreement as herein amended. The
execution, delivery, and effectiveness of this Amendment shall not, except as expressly provided herein, operate as a waiver of any rights of Lenders under any Loan Document, nor constitute a waiver under any of the Loan Documents. </FONT></P> <P
STYLE="margin-top:12px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B><I>Paragraph 9. <U>E<SMALL>NTIRE</SMALL> A<SMALL>GREEMENT</SMALL></U><SMALL></SMALL>.</I></B><B> T<SMALL>HIS</SMALL> A<SMALL>MENDMENT</SMALL>
<SMALL>REPRESENTS</SMALL> <SMALL>THE</SMALL> <SMALL>FINAL</SMALL> <SMALL>AGREEMENT</SMALL> <SMALL>BETWEEN</SMALL> <SMALL>THE</SMALL> <SMALL>PARTIES</SMALL> <SMALL>ABOUT</SMALL> <SMALL>THE</SMALL> <SMALL>SUBJECT</SMALL> <SMALL>MATTER</SMALL>
<SMALL>OF</SMALL> <SMALL>THIS</SMALL> A<SMALL>MENDMENT</SMALL> <SMALL>AND</SMALL> <SMALL>MAY</SMALL> <SMALL>NOT</SMALL> <SMALL>BE</SMALL> <SMALL>CONTRADICTED</SMALL> <SMALL>BY</SMALL> <SMALL>EVIDENCE</SMALL> <SMALL>OF</SMALL> <SMALL>PRIOR</SMALL>,
<SMALL>CONTEMPORANEOUS</SMALL>, <SMALL>OR</SMALL> <SMALL>SUBSEQUENT</SMALL> <SMALL>ORAL</SMALL> <SMALL>AGREEMENTS</SMALL> <SMALL>OF</SMALL> <SMALL>THE</SMALL> <SMALL>PARTIES</SMALL>. T<SMALL>HERE</SMALL> <SMALL>ARE</SMALL> <SMALL>NO</SMALL>
<SMALL>UNWRITTEN</SMALL> <SMALL>ORAL</SMALL> <SMALL>AGREEMENTS</SMALL> <SMALL>BETWEEN</SMALL> <SMALL>THE</SMALL> <SMALL>PARTIES</SMALL>. </B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT FACE="Times New Roman"
SIZE="2"><B><I>Paragraph 10. <U>Parties</U>.</I></B><B> </B>This Amendment binds and inures to Borrowers, Guarantors, the Agent, Lenders, and their respective successors and assigns. </FONT></P> <P
STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">The parties hereto have executed this Amendment in multiple counterparts to be effective as of the Effective Date. </FONT></P> <P
STYLE="margin-top:12px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><I>Remainder of Page Intentionally Blank. </I></B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman"
SIZE="2"><B><I>Signature Pages to Follow. </I></B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P>

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<TD VALIGN="top" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;&nbsp;&nbsp;3&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
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<TD VALIGN="top" NOWRAP ALIGN="right"><FONT FACE="Times New Roman" SIZE="2"><B>Sixth&nbsp;Amendment&nbsp;to&nbsp;Revolver&nbsp;Credit&nbsp;Agreement</B></FONT></TD></TR>
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 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">Signature Page to that certain Sixth Amendment to Credit Agreement dated as of the date first stated above, among
Westlake Chemical Corporation and certain of its domestic subsidiaries, as<I> Borrowers</I>, Bank of America, N.A., in its capacity as <I>Agent,</I> Required Lenders, and Guarantors. </FONT></P> <P
STYLE="margin-top:12px;margin-bottom:0px; margin-left:2%; text-indent:-2%"><FONT FACE="Times New Roman" SIZE="2"><B>BANK OF AMERICA, N.A.</B>, as the Agent and a Lender </FONT></P> <P
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<TD VALIGN="bottom"> <P STYLE="margin-bottom:1px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Robert Mostert</FONT></P></TD></TR>
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<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Name:</FONT></TD>
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<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Robert Mostert</FONT></TD></TR>
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<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Title:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Vice President</FONT></TD></TR>
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 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><I>Signature Page to </I></B><B><I>Sixth Amendment</I></B> </FONT></P>


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 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">Signature Page to that certain Sixth Amendment to Credit Agreement dated as of the date first stated above, among
Westlake Chemical Corporation and certain of its domestic subsidiaries, as<I> Borrowers</I>, Bank of America, N.A., in its capacity as <I>Agent,</I> Required Lenders, and Guarantors. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT
FACE="Times New Roman" SIZE="2"><B>GENERAL ELECTRIC CAPITAL CORPORATION, </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px; margin-left:2%; text-indent:-2%"><FONT FACE="Times New Roman" SIZE="2">as a Lender </FONT></P> <P
STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
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<TD VALIGN="bottom"> <P STYLE="margin-bottom:1px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Bond Harberts</FONT></P></TD></TR>
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<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Name:</FONT></TD>
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<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Bond Harberts</FONT></TD></TR>
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<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Duly Authorized Signatory</FONT></TD></TR>
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 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><I>Signature Page to </I></B><B><I>Sixth Amendment</I></B> </FONT></P>


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 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">Signature Page to that certain Sixth Amendment to Credit Agreement dated as of the date first stated above, among
Westlake Chemical Corporation and certain of its domestic subsidiaries, as<I> Borrowers</I>, Bank of America, N.A., in its capacity as <I>Agent,</I> Required Lenders, and Guarantors. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT
FACE="Times New Roman" SIZE="2"><B>THE CIT GROUP/BUSINESS CREDIT, INC., </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px; margin-left:2%; text-indent:-2%"><FONT FACE="Times New Roman" SIZE="2">as a Lender </FONT></P> <P
STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
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<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
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<TD VALIGN="bottom"> <P STYLE="margin-bottom:1px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ David Rothberg</FONT></P></TD></TR>
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<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Name:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">David Rothberg</FONT></TD></TR>
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<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Title:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Assistant Vice President</FONT></TD></TR>
</TABLE> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P>
 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><I>Signature Page to </I></B><B><I>Sixth Amendment</I></B> </FONT></P>


<p Style='page-break-before:always'>
<HR  SIZE="3" COLOR="#999999" WIDTH="100%" ALIGN="CENTER">

 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">Signature Page to that certain Sixth Amendment to Credit Agreement dated as of the date first stated above, among
Westlake Chemical Corporation and certain of its domestic subsidiaries, as<I> Borrowers</I>, Bank of America, N.A., in its capacity as <I>Agent,</I> Required Lenders, and Guarantors. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT
FACE="Times New Roman" SIZE="2"><B>PNC BANK, NATIONAL ASSOCIATION, </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px; margin-left:2%; text-indent:-2%"><FONT FACE="Times New Roman" SIZE="2">as a Lender </FONT></P> <P
STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="43%" BORDER="0">

<TR>
<TD WIDTH="12%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="87%"></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"> <P STYLE="margin-bottom:1px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Timothy S. Culver</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Name:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Timothy S. Culver</FONT></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Title:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Vice President</FONT></TD></TR>
</TABLE> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P>
 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><I>Signature Page to </I></B><B><I>Sixth Amendment</I></B> </FONT></P>


<p Style='page-break-before:always'>
<HR  SIZE="3" COLOR="#999999" WIDTH="100%" ALIGN="CENTER">

 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">Signature Page to that certain Sixth Amendment to Credit Agreement dated as of the date first stated above, among
Westlake Chemical Corporation and certain of its domestic subsidiaries, as<I> Borrowers</I>, Bank of America, N.A., in its capacity as <I>Agent,</I> Required Lenders, and Guarantors. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT
FACE="Times New Roman" SIZE="2"><B>WELLS FARGO FOOTHILL, LLC, </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px; margin-left:2%; text-indent:-2%"><FONT FACE="Times New Roman" SIZE="2">as a Lender </FONT></P> <P
STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="43%" BORDER="0">

<TR>
<TD WIDTH="12%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="87%"></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"> <P STYLE="margin-bottom:1px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Juan Barrera</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Name:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Juan Barrera</FONT></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Title:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Vice President</FONT></TD></TR>
</TABLE> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P>
 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><I>Signature Page to </I></B><B><I>Sixth Amendment</I></B> </FONT></P>


<p Style='page-break-before:always'>
<HR  SIZE="3" COLOR="#999999" WIDTH="100%" ALIGN="CENTER">

 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">Signature Page to that certain Sixth Amendment to Credit Agreement dated as of the date first stated above, among
Westlake Chemical Corporation and certain of its domestic subsidiaries, as<I> Borrowers</I>, Bank of America, N.A., in its capacity as <I>Agent,</I> Required Lenders, and Guarantors. </FONT></P> <P
STYLE="margin-top:12px;margin-bottom:0px; margin-left:2%; text-indent:-2%"><FONT FACE="Times New Roman" SIZE="2"><B>LASALLE BUSINESS CREDIT, LLC</B>, </FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px; margin-left:2%; text-indent:-2%"><FONT
FACE="Times New Roman" SIZE="2">as a Lender </FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="43%" BORDER="0">

<TR>
<TD WIDTH="12%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="87%"></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"> <P STYLE="margin-bottom:1px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Douglas Colletti</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Name:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Douglas Colletti</FONT></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Title:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Senior Vice President</FONT></TD></TR>
</TABLE> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P>
 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><I>Signature Page to </I></B><B><I>Sixth Amendment</I></B> </FONT></P>


<p Style='page-break-before:always'>
<HR  SIZE="3" COLOR="#999999" WIDTH="100%" ALIGN="CENTER">

 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">Signature Page to that certain Sixth Amendment to Credit Agreement dated as of the date first stated above, among
Westlake Chemical Corporation and certain of its domestic subsidiaries, as<I> Borrowers</I>, Bank of America, N.A., in its capacity as <I>Agent,</I> Required Lenders, and Guarantors. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT
FACE="Times New Roman" SIZE="2"><B>UBS AG, STAMFORD BRANCH, </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px; margin-left:2%; text-indent:-2%"><FONT FACE="Times New Roman" SIZE="2">as a Lender </FONT></P> <P
STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="43%" BORDER="0">

<TR>
<TD WIDTH="12%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="87%"></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"> <P STYLE="margin-bottom:1px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Luis Pistecchia</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Name:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Louis Pistecchia</FONT></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Title:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Director Banking Products Services, US</FONT></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"> <P STYLE="margin-bottom:1px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Douglas Gervolino</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Name:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Douglas Gervolino</FONT></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Title:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Associated&nbsp;Director&nbsp;Banking&nbsp;Products&nbsp;Services,&nbsp;US</FONT></TD></TR>
</TABLE> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P>
 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><I>Signature Page to </I></B><B><I>Sixth Amendment</I></B> </FONT></P>


<p Style='page-break-before:always'>
<HR  SIZE="3" COLOR="#999999" WIDTH="100%" ALIGN="CENTER">

 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">Signature Page to that certain Sixth Amendment to Credit Agreement dated as of the date first stated above, among
Westlake Chemical Corporation and certain of its domestic subsidiaries, as<I> Borrowers</I>, Bank of America, N.A., in its capacity as <I>Agent,</I> Required Lenders, and Guarantors. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT
FACE="Times New Roman" SIZE="2"><B>CREDIT SUISSE FIRST BOSTON, acting through </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px; margin-left:2%; text-indent:-2%"><FONT FACE="Times New Roman" SIZE="2"><B>its Cayman Islands Branch</B>, as a
Lender </FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="43%" BORDER="0">

<TR>
<TD WIDTH="12%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="87%"></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"> <P STYLE="margin-bottom:1px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Alain Dacust</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Name:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Alain Dacust</FONT></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Title:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Director</FONT></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"> <P STYLE="margin-bottom:1px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Denise L. Alvarez</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Name:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Denise L. Alvarez</FONT></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Title:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Associate</FONT></TD></TR>
</TABLE> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P>
 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><I>Signature Page to </I></B><B><I>Sixth Amendment</I></B> </FONT></P>


<p Style='page-break-before:always'>
<HR  SIZE="3" COLOR="#999999" WIDTH="100%" ALIGN="CENTER">

 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">Signature Page to that certain Sixth Amendment to Credit Agreement dated as of the date first stated above, among
Westlake Chemical Corporation and certain of its domestic subsidiaries, as<I> Borrowers</I>, Bank of America, N.A., in its capacity as <I>Agent,</I> Required Lenders, and Guarantors. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT
FACE="Times New Roman" SIZE="2"><B>DEUTSCHE BANK TRUST COMPANY AMERICAS, </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px; margin-left:2%; text-indent:-2%"><FONT FACE="Times New Roman" SIZE="2">as a Lender </FONT></P> <P
STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="43%" BORDER="0">

<TR>
<TD WIDTH="12%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="87%"></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"> <P STYLE="margin-bottom:1px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Marguerite Sutton</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Name:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Marguerite Sutton</FONT></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Title:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Director</FONT></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"> <P STYLE="margin-bottom:1px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Frank Fazio</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Name:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Frank Fazio</FONT></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Title:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Director</FONT></TD></TR>
</TABLE> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P>
 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><I>Signature Page to </I></B><B><I>Sixth Amendment</I></B> </FONT></P>


<p Style='page-break-before:always'>
<HR  SIZE="3" COLOR="#999999" WIDTH="100%" ALIGN="CENTER">

 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">Signature Page to that certain Sixth Amendment to Credit Agreement dated as of the date first stated above, among
Westlake Chemical Corporation and certain of its domestic subsidiaries, as<I> Borrowers</I>, Bank of America, N.A., in its capacity as <I>Agent,</I> Required Lenders, and Guarantors. </FONT></P> <P
STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0">

<TR>
<TD WIDTH="46%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="3%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="2%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="46%"></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" COLSPAN="5"><FONT FACE="Times New Roman" SIZE="2"><B>BORROWERS AND GUARANTORS:</B></FONT></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE&nbsp;CHEMICAL&nbsp;CORPORATION</B>,</FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman"
SIZE="2">a Delaware corporation</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" COLSPAN="3" NOWRAP> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE PVC CORPORATION,</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman" SIZE="2">a
Delaware corporation</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" COLSPAN="3" NOWRAP> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE VINYLS, INC.,</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman" SIZE="2">a
Delaware corporation</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B>NORTH&nbsp;AMERICAN&nbsp;BRISTOL&nbsp;</B><B>CORPORATION,</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT
FACE="Times New Roman" SIZE="2">a Delaware corporation</FONT></P></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"> <P STYLE="margin-bottom:1px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Albert Chao</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Albert Chao</FONT></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">President of the above Borrowers</FONT></TD></TR>
</TABLE> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P>
 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><I>Signature Page to </I></B><B><I>Sixth Amendment</I></B> </FONT></P>


<p Style='page-break-before:always'>
<HR  SIZE="3" COLOR="#999999" WIDTH="100%" ALIGN="CENTER">

 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">Signature Page to that certain Sixth Amendment to Credit Agreement dated as of the date first stated above, among
Westlake Chemical Corporation and certain of its domestic subsidiaries, as<I> Borrowers</I>, Bank of America, N.A., in its capacity as <I>Agent,</I> Required Lenders, and Guarantors. </FONT></P> <P
STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P><DIV ALIGN="right">
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="40%" BORDER="0">

<TR>
<TD WIDTH="6%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="93%"></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2"><B>NORTH AMERICAN PIPE CORPORATION,</B></FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2">a Delaware corporation</FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B>VAN BUREN PIPE CORPORATION,</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman" SIZE="2">a
Delaware corporation</FONT></P></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B>WESTECH BUILDING PRODUCTS, INC.,</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman" SIZE="2">a
Delaware corporation</FONT></P></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B>WESTECH PROFILES LIMITED,</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman" SIZE="2">a Delaware
corporation</FONT></P></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"> <P STYLE="margin-bottom:1px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Wayne D. Morse</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Wayne D. Morse</FONT></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">President of the above Borrowers</FONT></TD></TR>
</TABLE></DIV> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P>
 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><I>Signature Page to </I></B><B><I>Sixth Amendment</I></B> </FONT></P>


<p Style='page-break-before:always'>
<HR  SIZE="3" COLOR="#999999" WIDTH="100%" ALIGN="CENTER">

 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">Signature Page to that certain Sixth Amendment to Credit Agreement dated as of the date first stated above, among
Westlake Chemical Corporation and certain of its domestic subsidiaries, as<I> Borrowers</I>, Bank of America, N.A., in its capacity as <I>Agent,</I> Required Lenders, and Guarantors. </FONT></P> <P
STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P><DIV ALIGN="right">
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="40%" BORDER="0">

<TR>
<TD WIDTH="9%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="6%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="41%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="41%"></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="7"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE VINYLS COMPANY LP,</B></FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="7"><FONT FACE="Times New Roman" SIZE="2">a Delaware limited partnership</FONT></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2">GVGP, Inc., its general partner</FONT></TD></TR>
<TR>
<TD HEIGHT="16" COLSPAN="7"></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="7"> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE PETROCHEMICALS LP,</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman" SIZE="2">a
Delaware limited partnership</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2">Westlake&nbsp;Chemical&nbsp;Investments,&nbsp;Inc.,&nbsp;its&nbsp;general&nbsp;partner</FONT></TD></TR>
<TR>
<TD HEIGHT="16" COLSPAN="7"></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="7" NOWRAP> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE POLYMERS LP,</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman" SIZE="2">a
Delaware limited partnership</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2">Westlake&nbsp;Chemical&nbsp;Investments,&nbsp;Inc.,&nbsp;its&nbsp;general&nbsp;partner</FONT></TD></TR>
<TR>
<TD HEIGHT="16" COLSPAN="7"></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="7" NOWRAP> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE STYRENE LP,</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman" SIZE="2">a
Delaware limited partnership</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2">Westlake&nbsp;Chemical&nbsp;Holdings,&nbsp;Inc.,&nbsp;its&nbsp;general&nbsp;partner</FONT></TD></TR>
<TR>
<TD HEIGHT="16" COLSPAN="7"></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="7" NOWRAP> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B>WPT LP,</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman" SIZE="2">a Delaware limited
partnership</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2">Westlake&nbsp;Chemical&nbsp;Holdings,&nbsp;Inc.,&nbsp;its&nbsp;general partner</FONT></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="4"></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" COLSPAN="3"> <P STYLE="margin-bottom:1px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Albert Chao</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2">Albert Chao</FONT></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" COLSPAN="3" NOWRAP><FONT FACE="Times New Roman" SIZE="2">President&nbsp;of&nbsp;the&nbsp;general&nbsp;partners&nbsp;of&nbsp;the&nbsp;above&nbsp;Borrowers</FONT></TD></TR>
</TABLE></DIV> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P>
 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><I>Signature Page to </I></B><B><I>Sixth Amendment</I></B> </FONT></P>


<p Style='page-break-before:always'>
<HR  SIZE="3" COLOR="#999999" WIDTH="100%" ALIGN="CENTER">

 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">Signature Page to that certain Sixth Amendment to Credit Agreement dated as of the date first stated above, among
Westlake Chemical Corporation and certain of its domestic subsidiaries, as<I> Borrowers</I>, Bank of America, N.A., in its capacity as <I>Agent,</I> Required Lenders, and Guarantors. </FONT></P> <P
STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P><DIV ALIGN="right">
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="40%" BORDER="0">

<TR>
<TD WIDTH="6%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="93%"></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2"><B>GUARANTORS:</B></FONT></TD></TR>
<TR>
<TD HEIGHT="16" COLSPAN="3"></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2"><B>GVGP, INC.,</B> a Delaware corporation</FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE CHEMICAL HOLDINGS, INC.,</B></FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2">a Delaware corporation</FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE&nbsp;CHEMICAL&nbsp;INVESTMENTS,&nbsp;INC.,</B></FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2">a Delaware corporation</FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE MANAGEMENT SERVICES, INC.,</B></FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2">a Delaware corporation</FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE OLEFINS CORPORATION,</B></FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2">a Delaware corporation</FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE RESOURCES CORPORATION,</B></FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2">a Delaware corporation</FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE&nbsp;VINYL&nbsp;CORPORATION,</B></FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2">a Delaware corporation</FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE INTERNATIONAL CORPORATION,</B></FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2">a Delaware corporation</FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE NG I CORPORATION,</B></FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2">a Delaware corporation</FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE NG II CORPORATION</B></FONT></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2">a Delaware corporation</FONT></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"> <P STYLE="margin-bottom:1px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Albert Chao</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Albert Chao</FONT></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">President of the above entities</FONT></TD></TR>
</TABLE></DIV> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P>
 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><I>Signature Page to </I></B><B><I>Sixth Amendment</I></B> </FONT></P>


<p Style='page-break-before:always'>
<HR  SIZE="3" COLOR="#999999" WIDTH="100%" ALIGN="CENTER">

 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">Signature Page to that certain Sixth Amendment to Credit Agreement dated as of the date first stated above, among
Westlake Chemical Corporation and certain of its domestic subsidiaries, as<I> Borrowers</I>, Bank of America, N.A., in its capacity as <I>Agent,</I> Required Lenders, and Guarantors. </FONT></P> <P
STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P><DIV ALIGN="right">
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="40%" BORDER="0">

<TR>
<TD WIDTH="11%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="88%"></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B>GEISMAR HOLDINGS, INC.,</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman" SIZE="2">a Delaware
corporation</FONT></P></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE&nbsp;CHEMICAL&nbsp;MANUFACTURING,&nbsp;INC.</B>,</FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT
FACE="Times New Roman" SIZE="2">a Delaware corporation</FONT></P></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE CHEMICAL PRODUCTS, INC.,</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman" SIZE="2">a
Delaware corporation</FONT></P></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2"><B>WESTLAKE DEVELOPMENT CORPORATION,</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman" SIZE="2">a
Delaware corporation</FONT></P></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"> <P STYLE="margin-bottom:1px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ R. Michael Looney</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">R. Michael Looney</FONT></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">President of the above entities</FONT></TD></TR>
</TABLE></DIV> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P>
 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><I>Signature Page to </I></B><B><I>Sixth Amendment</I></B> </FONT></P>

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