Form of Long-Term Cash Performance Award Letter for 2018 Executive Officer Awards

Relationship to Plan. This Performance Award is subject to all of the terms, conditions and provisions of the Westlake Chemical Corporation 2013 Omnibus Incentive Plan (the “Plan”) and administrative interpretations thereunder, if any, which have been adopted by the Administrator and are in effect on the date hereof. Except as defined herein, capitalized terms shall have the same meanings ascribed to them under the Plan.

Payment Schedule.

The amount of the Performance Award shall be calculated based on the Company’s achievement of certain performance conditions, as set forth on Exhibit A (the “Performance Condition”) during the 2018-2020 performance cycle, which is the period from January 1, 2018 through December 31, 2020 (the “Performance Cycle”). The Performance Award shall be paid to you in cash as soon as practicable following the date the Administrator determines to what extent the Performance Conditions were satisfied, provided, however, that you are employed by the Company or any of its Subsidiaries on such payment date.

The Performance Award shall be paid to you at the target level, irrespective of the limitations set forth in subparagraph (a) above, in the event of your termination of employment with the Company or any of its Subsidiaries due to death, with such amount multiplied by a fraction, the numerator of which is the number of days of employment with the Company or any of its Subsidiaries you completed during the Performance Cycle and prior to your death, and the denominator of which is the

The Performance Award shall be paid to you, irrespective of the limitations set forth in subparagraph (a) above, in the event of your termination of employment with the Company or any of its Subsidiaries due to Normal Retirement, with such amount multiplied by a fraction, the numerator of which is the number of days of employment with the Company or any of its Subsidiaries you completed during the Performance Cycle and prior to your Normal Retirement, and the denominator of which is the total number of days in the Performance Cycle. To the extent earned based on the Performance Condition, such Performance Award shall be paid to you on March 15^th of the year immediately following the end of the Performance Cycle. For purposes of this Performance Award, “Normal Retirement” shall mean your termination from employment with the Company and its Subsidiaries for any reason after you have (a) attained at least 65 years of age, and (b) been employed by the Company or a Subsidiary for a continuous period of 10 years or more ending on the date of your termination.

Forfeiture of Performance Award. If your employment with the Company or any of its Subsidiaries terminates other than by reason of death or your Normal Retirement, your Performance Award shall be forfeited.

Withholding. At the time of the payment of the Performance Award, the Company shall withhold an amount of cash equal to the amount necessary to satisfy the minimum federal, state and local tax withholding obligation with respect to this Performance Award.

Assignment of Performance Award. Your rights under the Plan and this Performance Award are personal; no assignment or transfer of your rights under and interest in this Performance Award may be made by you other than by will or by the laws of descent and distribution.

No Employment Guaranteed. No provision of this Performance Award shall give you any right to continued employment with the Company or any Subsidiary.

Governing Law. This Performance Award shall be governed by, construed, and enforced in accordance with the laws of the State of Texas.

Clawback or Recoupment. This Performance Award and any cash delivered hereunder are subject to clawback or recoupment as required by applicable law or Company policy.

Section 409A. Any payments under Paragraph 2(a) or 2(b) of this Performance Award are intended to be exempt from Section 409A of the Code, by compliance with the short-term deferral exemption as specified in Treas. Reg. § 1.409A-1(b)(4). Any payment under Paragraph 2(c) of this Performance Award is intended to be compliant with Code Section 409A as being paid pursuant to a specified time or fixed schedule under Treas. Reg. § 1.409A-3(i). The provisions of this Performance Award shall be administered, interpreted and construed accordingly.

Definition of Performance Condition. The Performance Condition for the 2018-2020 performance cycle shall be based on the greater of the average annual economic value added (“EVA”) results for Westlake Chemical Corporation and relative total shareholder return (“TSR”) as compared to a peer group of companies. EVA is equal to net operating profit after tax (“NOPAT”) less a capital charge based upon the weighted average cost of capital. TSR means stock price growth for a defined measurement period, with any dividends paid.

Calculation of Performance Award. The amount of the Performance Award shall be determined as set forth on the following chart:

Adjustments. If a change in control of the Company occurs, and as a result the Administrator determines that the relative TSR calculation would no longer be fairly representative of the Company's performance, the Administrator may make such adjustments to the Performance Condition as it deems necessary in the calculation of the Company’s TSR.