Blog/Articles

In many sports, we’ll commonly hear coaches say that it’s time to go back to the “fundamentals” when teammates or the team is struggling to with obtaining the desired on-field results. This is true even for professional athletes, who have gone through all the most basic motions thousands of times, yet their pro coaches might say it’s time those basics are revisited, much to the collective chagrin of the team. I believe this is true for any profession.

Win or lose, fundamentals are, well, fundamental to the way the game is played – both at an amateur level, and yes, also as a pro. In this article, we go back to examine the basics of WRT training to look at the basics of moisture meter hermeneutics (aka interpretation). As we are all aware, there are both invasive means to measure – with penetrating pins, and non-invasive means – non-penetrating surface readings.

Now let’s look at the difference and how to parse and differentiate moisture content from moisture level, and why it’s important to understand and communicate those differences to others.

By far, most moisture meters are calibrated to measure the quantity of moisture in wood and this is expressed as a percent moisture content (%MC) in the wood (Larsen, 2014). This is done invasively, using pins, and the reading is expressed as a percentage of the weight of the water compared to the weight of the oven dried sample of wood. The value “percent moisture content” is only appropriate to use for wood moisture readings.

When taking moisture readings with pins for non-wood based products such as drywall, plaster, concrete and bricks, the moisture content reading will be termed a “wood moisture equivalent” (WME). This term was coined by General Electric, who manufactured the Protimeter moisture meter, and then the WME term became the commonly used term in the industry. The WME is the moisture level in any building material as if it were in close contact and in moisture equilibrium with wood, expressed as a percent moisture content (%MC) of wood. Therefore, any reading above 20% indicates a hazardous condition that needs further investigation (Larsen, 2014).

Lastly, “moisture level” is an expression to indicate a relative reading that is performed by a moisture meter in a non-invasive way – think surface level reading without the pins. It is the measurement of the amount of moisture in a building material on a relative scale. Depending on make and model of moisture meter, that scale can range from anything such as 0-60 or 60-999 as two commonly used examples. These numbers do not indicate percentages by any means, and it is very important that restorers relay the reading to the client and/or adjustor in the proper way. Moisture level is not the same thing as moisture content and confusing the two in an effort to simplify a message, could backfire.

An example of this is perhaps you are summoned to a court of law and a prosecuting attorney is investigating your work. He or she will research the proper use of industry standards and interpretation of results. How those results were documented helps to provide clarity to your story from your side as a restoration pro. The important takeaway here is that moisture level does not reflect any quantified measure of moisture in the material, which is why the terms “points” or “level” is used to indicate the moisture reading.

It might not seem like a big thing, understanding the difference between %MC, %WME, or the relative scale. But understanding these key differences could be the difference between a job documented well, or a job documented well that ends up in court but with evidence that has substance, makes sense, is defensible, and clarifies your story.