Every home owner at some point will have to replace some areas of rotted out wood at their homes. All wood has the potential to rot. Rot damage is caused by high moisture content of wood. If the moisture content of wood rises to over 20% wood rot is very likely to develop. Wood rot is very common around door and window trims and in basements with water infiltration and seepage problems. Wood rot essentially is caused by a fungus. Fungus like mold needs several favorable conditions to survive. One condition is that it needs a food source which is the wood itself. The fungus needs to breath so it needs air and it needs temperatures in the range of 50 degrees to 110 degrees F. Of course the fungus needs high moisture to grow and propagate. Moisture is the factor that we have the most control over. If we stop the moisture we stop the wood rot.
Only wood with high moisture content can rot. Dry wood does not rot because conditions are not right. Often people refer to dry wood with checking across its grain as dry rot. This is actually called brown rot which causes this type of cracking against the grain. After the fungus takes all of the nutrients from the wood the wood is left powdery and very brittle.
Wood rot fungus is different from mold. Molds themselves do not cause wood decay. Mold has its own set of issues many of which can negatively effect the health of individuals in the house hold.