Green lumber, which is a term also referred to as wet lumber, is wood that has a higher moisture content, and is used in construction.
When a tree has been freshly cut, it tends to hold a lot of water in its cells. A term used for the water that has collected in these cells is ‘free water’. After the tree has been cut, this ‘free water’ will slowly evaporate. It will stop this process when it has reached the same level of moisture as the environment it is in. This is a process which is referred to as EMC (equilibrium moisture content).
If we want to use dry lumber in construction, we would naturally expect it to have had time to reach EMC before being used. This is not the case when it comes to green lumber. As the name suggests, it has not usually had the required amount of time to reach EMC before use. Generally, after processing, green lumber has been wrapped in plastic and stored, which hampers the process of evaporation. The result of this is that the wood is used while still retaining a lot of moisture.
There are some areas of the country where green lumber will often be used. These are drier and hotter areas like Arizona and areas of California, where that wood will dry out much quicker.
Perhaps you’re thinking “why use this type of lumber in construction then?” A very simple reason for this is that it is normally cheaper to use. It is also a softer wood which makes things like hammering nails a lot easier, and less prone to splitting
Maybe after this brief description, you are wondering what kinds of problems could possible arise from the use of green lumber. Perhaps you’re wondering if it would be right for you? In our next blog we will address these questions.