Why decks turn gray and green
That silvery-gray patina on old decks is UV damage combined with mildew feeding on trapped moisture and pollen. Green patches are algae — the same organism you see on shady sidewalks. Both are fixable. A professional deck cleaning removes the organic growth, lifts weathered wood cells, and exposes the fresh wood underneath. From there you can seal it, stain it, or just enjoy the natural color.




