Our Coin Flex Tiles have been installed all over the U.S. and Cannada, and snow, ice, and salt do not affect the tiles one bit. These tiles interlock very tightly, so water, in most instances does not seep underneath the tiles. These tiles are mold and mildew resistant, so you wouldn't have to worry about it growing on your new flooring. The only time you would see mold or mildew would be in the rare case some food or other organic material got trapped underneath the tiles. If your concrete floor has a high moisture content, what you will see are the salts and minerals trapped under tiles; This typically looks like white mold, but it not. You would need to seal your concrete floor and then clean the tiles with Purple Power.