Six months ago my flooring installation subcontractor glued bamboo flooring directly to the concrete slab in a condo we were remodeling. All looked great for 3 months then in 1 room a large section of the bamboo flooring bubbled up about 6-8 inches off the concrete. I removed that floor and found that the grain in the bamboo had become darker and mold was growing. Several months went by and another room had the same problem. After inspection I noticed that grain in the bamboo has become very dark and the surface texture is detriorating and showing the wiood grain. Does anyone out there have a similar experience that they could share? This will cost a substantial amount of money to repair and we did a thorough analysis before we decided to glue down the bamboo directly to the concrete. I'm wondering if there is an existing problem with bamboo out of China.