Experimental roof panels, made by using preservative-treated shakes for an exposure test, were used to study the first-year depletion of the active ingredients of the preservatives. After 8 months of exposure, all shakes retained concentrations of the preservatives sufficient to prevent biological deterioration. Most preservative depletion occurred from the butt end of the shakes, where the original retentions were much higher than in the middle parts of the shakes. Losses of the preservatives were much lower from the middle parts of the shakes, and for most treatments the losses were negligible. According to the analyses of rainwater collected from roof panels, the leaching leveled off to a relatively low level after 6 to 8 months of exposure, and remained at this level for at least an additional year. Includes testing procedures for fungicides: chromated copper arsenate, ammoniacal copper arsenate, pentachlorophenal, and disodium octaborate tetrahydrate (timbor). -- AATA