A seven-year study compares protection offered to Douglas fir piles by pentachlorophenol, creosote and fluor-chrome-arsenic-phenol (FCAP) in Seattle, Washington and Gulfport, Mississippi. Some deep checked timber showed decay when treated with the first two, but no decay when treated with the last. Some timbers treated with FCAP were in good condition after 17 years. Creosote appears to protect planking better from heavy traffic, but not from decay developing in deep checks. FCAP may be used to inhibit decay in deep checks. -- AATA