Latest News

Calculate spans for preserved wood joists

Finding the proper span for preserved wood joists in decks and other structural applications is easy with the new Deck Joist Span Calculator, available on our website. The Excel-based calculator determines spans for 2-inch preserved wood from 4 inches to 14 inches in width under common loads. It can also adjusts the spans for incised wood, as required in building codes. The calculator was created in cooperation with Western Wood Products Assn., which maintains span tables and other design information on Western lumber species. Click here to download this new tool.

Wood coatings research updated

A 24-month report on research on the performance of wood coatings is now available.

The research conducted by Oregon State University compares the performance of coatings such as BluWood, TimberSil and Eco Red Shield compared to pressure-treated wood in protecting the wood against termites and decay fungi. The updated report reviews the development of decay fungi on samples, which typically takes 18 months to two years to begin appearing on wood, depending on conditions.

Click here to review the updated research report.

SDSs for wood preservatives available

Safety data sheets, or SDSs, for wood preservatives can be downloaded or requested from a new Find SDS section on our sister site, The new sheets, required by OSHA regulations, replace the Material Data Safety Sheets (MSDS) and must be provided to downstream users to communicate information on the hazards of the chemicals in the preservatives.

Click here to request or download an SDS for each of the commonly available wood preservatives available today.

New PreserveTech on field treating released

Get the most current information on field treating preserved wood in a new PreserveTech technical sheet.

The one-page sheet describes the recommended field treating for cuts and holes made in preserved wood during construction and Includes links to recommended preservatives for field treating.

Download the new sheet today from our Technical Library at

Corps settles, removes treated wood ban

The U.S. Army Corps of Engineers has settled a lawsuit brought by the preserved wood industry and has agreed to allow the use of preserved wood over and near waters or wetlands.

The settlement removes restrictions on using preserved wood in projects located in the agency's Oregon and Alaska districts.

Click here to review the announcement made by the Corps.


About Western Wood Preservers Institute - WWPI

Headquartered in Vancouver, Washington, the Western Wood Preservers Institute (WWPI) is a nonprofit member trade organization representing the interest of the preserved wood products industry throughout western North America for more than 60 years. The membership consists of companies that either manufacture products, are directly affiliated or provide a service to the preserved wood industry. The primary activity areas of the WWPI include regulatory and market outreach programs aimed at sustaining a viable western North America preserved wood industry.

WWPI Purpose Statement

To support and sustain the production and use of treated wood products manufactured in western North America.

WWPI Mission Statement

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It is the WWPI mission to protect and promote the manufacture and markets for preservative treated wood products produced by the industry in western North America. This shall be accomplished through coordinated industry strategies, utilizing the best scientific information available to:
  • Increase public and consumer appreciation and confidence in our products and our industry;
  • Secure reasonable and economic federal, state, provincial and local environmental regulation regarding our products and processes;
  • Promote the development and application of codes, standards and Quality Assurance programs to ensure products best meet the needs of the users.

WWPI Environmental Code

Members of WWPI share the public concerns for a sound economy, healthy environment and good stewardship of all natural resources.
To that end, the members strive to achieve the following principals:
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  • To produce high quality products which, when used as intended, will significantly extend the useful life of the treated wood material.
  • To operate facilities in a manner which meets or exceeds applicable federal, state or provincial regulations.
  • To support and utilize research aimed at developing products and processes which are consumer and environmentally friendly.
  • To participate in the development of public regulations and product standards which are based on sound scientific information and balance the long term need for a strong economy and healthy environment.
  • To actively support the reuse and recycling of treated wood products.


The Western Wood Preservers Institute believes the information contained on this Web Site to be based on up-to-date scientific and economic information and is intended for general informational purposes. In furnishing this information, the Institute make no warranty or representation, either expressed or implied, as to the reliability or accuracy of such information; nor does the Institute assume any liability resulting from use of or reliance upon the information by any party. This document should also not be construed as a specific endorsement or warranty, direct or implied, of treated wood products or preservatives, in terms of performance, environmental impact, or safety. The information contained herein should not be construed as a recommendation to violate any federal, provincial, state or municipal law, rule or regulation, and any party using or producing pressure treated wood products should review all such laws, rules or regulations prior to using or producing treated wood products.

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