Plain and simple, rotten wood is wood that has decayed. Decay is caused by fungi which not only grow on wet wood, but take their nourishment from it. There are four conditions that must be present for rot to occur in wood.
1. A source. Decay causing fungi are everywhere. They are propagated by microscopic spores which travel through air.
2. Moisture. Fungi need wet wood to feed on. They can live only on wood that comes in direct contact with water, not wood that only swells from high humidity.
3. Temperature. Fungi need a temperature of 50 to 120 degrees in order to live and grow.
4. Darkness. Fungi thrive in the dark. Basements and underneath porches are areas where rot is likely to occur due to the lack of light.
If any of these conditions were to be removed, then rot can not occur. Most of them however, can not be controlled. The only exception is moisture. If the basement or crawlspace area of the house is effectively waterproofed and other steps are taken to prevent water from reaching these areas, then the fungi will die.
The best method for preventing rot is to look for tell-tale signs of moisture or fungi. Peeling paint or stains on wood means that water has been present. Some fungi are white and are easily recognizable. When first noticed, steps to dry up the area must be taken.
Porches and deck areas are practically impossible to keep dry. Treating the wood with a quality wood preservative or sealing it with paint helps prevent rot. Another solution is to use pressure treated lumber when repairing or replacing wood. The preservatives are forced into the wood under pressure to take the place of water in the fibers. Fungi can not live in this type of wood and insects do not want to eat it.
Carpenter ants and termites are the two types of insects that eat wood. Of these two, termites are the worst because they feed on the wood. Carpenter ants only chew enough to make a nest and they eat only on wet wood. Drying out the wood and spraying the ants with an appropriate insecticide will usually get rid of them.
Termites can eat dry wood and get water from the soil where they make their nest. Typically, termites build tunnels in mud along foundation walls and discovering these tunnels may indicate that termites are in the house. If the tunnels are destroyed, the termites will die.
If evidence of termites is found, it may be best to call in a professional exterminator to help rid the home of these pests.
Remember, always work safely.