Protecting wood decks from biodegradation and weathering : evaluation of deck finish systems

Abstract

Mildew resistance, water repellency, and overall finish appearance were evaluated for 32 deck finishes on western redcedar (Thuja plicata D. Donn.) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) after 12, 21, and 39 months of outdoor exposure in western Oregon. The finishes were either solvent-borne or waterborne; were ei- ther clear, tinted, or lightly pigmented; and were, in general, formulated to penetrate the wood surface. Mildew resistance was generally good for most of the finishes through the 21-month evaluation. Water repellency was fair at the 12-month evaluation, but in almost all cases had disappeared after 21 months. Overall appearance varied considerably for the finishes. Clear finishes generally were in only fair condition after 12 months; however, several tinted and lightly pigmented finishes were in good condition after 21 months. All finishes were in poor condition after 39 months. Service lives of these finish types can be extended to the 2-year range, but additional research and development is needed to achieve a longer service life. Given the low solids content and transparent nature of these finish types, a 2- to 3-year service life should be considered excellent in a fully exposed horizontal exposure.

Citation

Morrell, J. J.; Schneider, P. F.; Williams, R. Sam. 2001. Protecting wood decks from biodegradation and weathering : evaluation of deck finish systems. Forest products journal. Vol. 51, no. 11/12 (Nov./Dec. 2001).:p. 27-32.