40 Construction Lumber Moisture Content Update

This pinless moisture meter uses an analog display to provide easy to read assessments of moisture content in wood and other building materials.

Construction lumber moisture content. Below 12 readings in this range are common to kiln or oven dried woods and furniture grades of wood and represent dry conditions. Understanding moisture content can be useful for a number of common materials such as wood ceramics soil and so on. When a tree is still growing the tree may have more moisture in it than ovendry wood fiber resulting in moisture contents greater than 100. Using wood with a moisture content above 14 isn t recommended because it may have detrimental long term effects on the construction.

Sometimes the weight of the water in a piece of wood exceeds the weight of the dry wood in which case the moisture content exceeds 100. Moisture content of the wood at delivery. Most interior wood is in this range. The term moisture content or water content refers to the amount of water that is contained in the pores voids of a material it is usually expressed as the percentage by mass of the water present relative to the material s dry weight.

12 16 readings in this range are common to lumber during construction. The amount of moisture in wood is often expressed as a percentage of the weight of the wood when the oven drying method is used. Up to 25 30 moisture content the water in wood is chemically bound to the wood fibres. For example fresh cut trees can have a wood moisture content over 200 while completely dried wood will have a wood moisture content of 0 and wood in buildings usually has a wood moisture content of 5 to 15.

What is moisture content of lumber. Leed ap the founder of built environments inc wood moisture content as high as 15 can cause corrosion of metal fasteners and at 16 may lead to fungal growth. Moisture content is measured using a moisture meter. Failure to check your delivered material means you have no chance of anticipating movement problems.

Basically wood moisture content is the weight of water in a piece of wood expressed as a percentage of oven dry weight of wood. As wood is cut and exposed to air the. If you re planning to use the lumber for outdoor projects airdrying outdoors is fine. The only way to accurately predict wood movement is to know the mc of the material when you receive it.

Thus a piece of wet timber whose weight is half dry wood and half water has a moisture content of 100. Air dry isn t dry enough for indoor use. In fact according to m. The lower the moisture content readings less lumber drying and shrinkage will take place over time and as a result you ll see fewer settling.

Although you can accept a lumber moisture content reading of 19 ideally you should aim for moisture content below 15 for kiln dried lumber and less than 17 for any green pressure treated lumber. Wood in buildings usually has a wood moisture content of 5 to 15.