EXHIBIT 21

SUBSIDIARIES OF WESTLAKE *

Name of Subsidiary	State or Other Jurisdiction of Incorporation or Organization	Names Doing Business
North American Pipe Corporation	Delaware	North American Pipe Corporation    and NAPCO
North American Specialty Products LLC	Delaware	North American Specialty Products LLC
Vinnolit Benelux-France B.V.B.A.	Dendermonde, Belgium	Vinnolit Benelux-France B.V.B.A.
Vinnolit GmbH & Co. KG	Ismaning, Germany	Vinnolit GmbH & Co. KG
Vinnolit Hillhouse Ltd.	Lancashire, England	Vinnolit Hillhouse Ltd.
Vinnolit Italia S.r.L.	Milan, Italy	Vinnolit Italia S.r.L.
Vinnolit Ltd.	United Kingdom	Vinnolit Ltd.
Vinnolit Schkopau GmbH	Ismaning, Germany	Vinnolit Schkopau GmbH
Westech Building Products, Inc.	Delaware	Westech Building Products, Inc.
Westech Building Products ULC	Canada	Westech Building Products ULC and    Westech Building Products Limited
Westlake Chemical OpCo LP	Delaware	Westlake Chemical OpCo LP
Westlake Chemical Partners LP	Delaware	Westlake Chemical Partners LP
Westlake Germany GmbH & Co. KG	Ismaning, Germany	Westlake Germany GmbH & Co. KG
Westlake Longview Corporation	Delaware	Westlake Longview Corporation
Westlake Management Services, Inc.	Delaware	Westlake Management Services, Inc.
Westlake Petrochemicals LLC	Delaware	Westlake Petrochemicals LLC,    Westlake Petrochemicals LP and WPE
Westlake Polymers LLC	Delaware	Westlake Polymers LLC,    Westlake Polymers LP and WPE
Westlake PVC Corporation	Delaware	Westlake PVC Corporation
Westlake Styrene LLC	Delaware	Westlake Styrene LLC and    Westlake Styrene LP
Westlake Supply and Trading Company	Delaware	Westlake Supply and Trading Company
Westlake Vinyls Company LP	Delaware	Westlake Vinyls Company LP
Westlake Vinyls, Inc.	Delaware	Westlake Vinyls, Inc.,    Westlake Monomers and WCAO
WPT LLC	Delaware	WPT LLC and WPT LP
Suzhou Huasu Plastics Co., Ltd. **	People’s Republic of China	Suzhou Huasu Plastics Co., Ltd.    and Huasu

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* Westlake has elected to omit the names of certain subsidiaries. None of the omitted subsidiaries, considered either alone or together with the other omitted subsidiaries of its immediate parent, constitutes a “Significant Subsidiary” as set forth in Section 601(b)(21) of Regulation S-K.

** Westlake owns 59% of this entity but accounts for it using the equity method.