Most people think that wood rots when it gets wet. This is a myth as it is not water alone that rots wood. Timbers have been pulled out of rivers and seas that are hundreds of years old and have not decayed into oblivion so what is it exactly that makes wood rot?
Water is only 1 ingredient of a number that all need to come together. What causes wood to rot is actually a fungus, which is a living thing and for living things to survive like us it needs water (but not too much), food (the wood itself), oxygen and the right temperature.
When these conditions are right the fungus will happily eat away at the wood and when the fungi begins to decay it will release enzymes and chemicals, which will speed up the rotting even further as it breaks down the compounds in the wood fibers.
When you take each of these factors on their own you can see why it is so important that wood isn’t touching the floor where it can sit in pools of water and not receive a good flow of air to dry it out. If wood cannot breath any fungi on the wood will die and decay the wood at a faster rate. Warmer conditions will also naturally accelerate any fungi growth as fungi favour war conditions over cold.
So why do some types of wood last longer than others? The answer is in their chemical compounds. Some types of wood like larch and cedar are high in natural resins, which are poisonous for fungi where as soft woods like pine contain very little so are a fungi’s dream if untreated.
If you are going to use soft woods like pine outside it is important to get pressure treated pine, which is where the wood has been through a vacuum which allows preservatives to penetrate deep within the wood fibers. The preservative then acts as the natural resin does. It is something that is poisonous to the fungi and therefore prevent its growth.
There are different types of rot like wet rot, brown rot, whit rot and dry rot. The principle is the same throughout the only difference is the type of fungi present in the wood.
To prevent rot setting in to your timber the best cure is preventative action as rot can be a costly beast in the future to repair and replace sections of timber, especially if they are structural.