Hello. I recently purchased my home, (November of '09). I was actually renting this place before I purchased it. Anyway, when I was still leasing the house, I striped old caulking from the master bath shower (because it was quite ineffective, and had intrusion issues), allowed the shower to dry out, (by using the common bath in the hallway) and recaulked to seal the shower. I have decided to remodel the master bath. I am in the first stages of demolition and was curious to see just what the damage really was. The sub-floor was rotting just under the shower pan curb, some of the sub-floor under the framed walls is rotten also. I have inspected the joists that are directly under the bad sub-floor where the curb was. I removed some of the sub-floor, about a 4'x2' space, and have a pretty good visual on the joists. On the sides, the joists are dark in colour from where moisture came through the sub-floor. I took a screwdriver and poked around the joist and aside from the discolouration on the sides, they are solid. However, it is a different story on the top of the joist. There seems to be some sort of mildew or mold on top of the joist, where it was in contact with the rotten sub-floor. This area is white on the surface and spongy to roughly 1/16" to 1/8" deep. I knew that this was going to be a problem area, because our house inspector informed us of the possible damage. He said that the sub-floor might need to be removed and joist treated with Timbor. Before I treat it with Timbor, do I need to remove any of the mold or surface wood? If remove all the surface wood, do I even need to treat it with Timbor? Or is the wood hopeless and needs to be removed altogether and replaced? Is just slicing away the bad surface sufficient according to building codes (I'm in California). Are there any other treatments that I can use on the wood after scraping off the surface? Any help on this matter would be greatly appreciated. Thanks!