Marina Dock Age: Fortress Building Products uses bamboo flour instead of traditional wood flour in its cellular PVC and composite decking. “Bamboo, from an environmental standpoint, is easy and replaceable. On the performance side, there is much less moisture absorption in bamboo than in wood flour. Bamboo filler with our composite performs better specifically in a water environment where you have that potential for moisture absorption,” said Toby Bostwick, vice president of product and brand, who added that because of its performance around water, PVC is becoming an up-and-coming choice for docks.