♦ Deck boards are 5/4” x 6” solid planks for both cedar and WPC. ♦ Decking products have a 25-year service life with no coatings or board replacements (subsequent sensitivity analyses considered the impact of replacing 20% of cedar boards and periodically staining the cedar) ♦ All products are disposed of in a landfill at the end of life. ♦ All environmental flows are attributed 100% to the decking products, although in the case of cedar some flows could fairly (and properly) be allocated to co-products such as mulch or shavings. ♦ All activities or building elements common to all products (such as transportation, installation and use, and end of life disposition) are considered equivalent and ignored. ♦ The western red cedar decking is produced in the Pacific Northwest region of the U.S. while the WPC plastic decking is produced in the eastern U.S. Considered in the assessment for both cedar and WPC decking were resource extraction (and collection of plastic for recycling in the case of WPC), reforestation (in the case of cedar decking), resource transportation, manufacturing, transportation to site (for three hypothetical building site locations), installation, use, maintenance (excluding cleaning since annual cleaning is recommended for both cedar and WPC decks), and end-of-life disposal.