I too have the mold issue with a TimberTech deck that was installed in the fall of 2005 ~ paid over $16K for a maintenance free deck & I was also instructed NOT to powerwash it. Now Timbertech is telling me to power wash it with Corte Clean to remove the mold!!! Why would this deck mold and why would I have even considered this investment if it was capable of molding??? I haven't taken any action to remove/clean this as I don't want to destroy any evidence of this mold and would love to see a class action suit filed against them. This mold is inside of the product and not caused by environment as they stated. I am on a walkout with my deck being on the 2nd level (of a 3 story) of my home, facing dead South in sunny & dry climate just SE of Denver...yes, snow in winter but overall not high moisture area here.