Timber moisture measurement

Renewable resource, the wood used in construction, timber, contributes to reduce greenhouse gases, in particular CO2, by  trapping carbon.

There are several methods to measure timber moisture.

Resistance moisture measurement

Wood moisture level is inversely proportional to the electrical resistance measured between two points: the more moisture there is, the less resistance.
Recommended by the EN 13183-2 standard, this moisture measurement is based on the circulation principle of an electric current. Moisture meters that use this principle have two electrodes that are thrust into the wood. With insulated pins, the moisture meters allow a precise measurement of the moisture level at the wood core.

Measuring wood water content with drying and weighing

This method for measuring moisture consists of taking a wood sample (between 100 and 200 g), weighing it then drying it. The wood moisture level (H %) is then assessed using the following formula: H %= (mh-mo/ mo) *100 % ("mh" is the weight of the wet wood and "mo", the weight of oven-dried wood).
This method is stressful and destructive to the material.

Capacitive moisture detection

When held against the wood surface, the moisture detector emits a high frequency signal. The moisture tester interprets the reflective or absorbent level of an electrical field, based on the temperature and moisture of the wood. This method must be carried out on a flat surface and detects moisture rather than measures it.
Whatever moisture measuring method is used, producers must comply with existing standards and put in place a Factory Production Control (FPC) system, so as to ensure compliance of the wood products they put on the market.
Also, to comply with the EN 14081* standard, they must guarantee the aptitude of all personnel responsible for classifying wood and for checking moisture measuring instruments used in sawmills that produce wood for wooden structures.

* Law dated 3 July 2006 relating to some wooden structures