process are registered by the EPA as a non-restricted use pesticide and do not require Proposition 65 labeling in California. Products treated with micronized copper preservatives, such as YellaWood® brand products, as described in ESR-1980 and ESR-2240 are building code compliant.
When it rains, the unprotected wood cells absorb water causing the cells to expand. When the deck dries, the wood's cells shrink. This continuous cycle of expansion and contraction ultimately causes cracking in the boards on your deck. Freeze and thaw cycles will also cause similar damage.
Constant exposure to the sun discolors the surface and accelerates wear by breaking down fibers in the wood. Throw in rain or snow and there's warping, rotting and cracking to contend with. Shade can spell trouble too, prolonging moisture's stay, which allows mold and mildew to turn the deck's surface a dingy gray or black.
Most wood products will look good for 2 or 3 years in our climate. During that time it will turn to a gray color and start to look dirty. Our advice is to have the deck protected as soon as it is built. If it was not protected when it was built, have it cleaned and protected now!