How to Interpret Moisture Meter Readings on Different Scales
The most common moisture meter scales are the wood scale and what is commonly referred to as a reference scale. However, even within these categories, scales may differ somewhat from manufacturer to manufacturer and even from one type of meter to another.
The key difference between these scales is that the wood scale provides actual moisture content of the material with a percentage reading, whereas the reference scale provides only relative readings. Wood, for example, is generally considered “safe” with a moisture content of between 8% and 11% in most parts of the U.S., while drywall must be below 1% moisture content to be considered structurally sound and free from mold or decay.
The Wood Scale
Most wood moisture meters are calibrated to cover a range of 6% to 40% moisture content, though this may vary slightly by model and manufacturer. Different species of wood may measure differently based on their electrical characteristics, but the basic wood scale is generally reliable for any construction-grade lumber. Some meters also have species correction charts or built-in species correction capabilities to allow you to correct readings for a variety of wood species.
The differences that may require translation when testing different species of wood become even more significant when entirely different materials are involved. Thus, a wood-scale meter should not be used to measure concrete, drywall or other building materials.
The Reference Scale
Often, a moisture meter’s reference scale will range from 0-100, but that reading should not be confused with a percentage. Some meters use a 0-300 reference scale, so readings taken on a reference scale do not correlate to one another. The reference scale does not offer exact measurements in terms of %MC, but instead serves two purposes. First, a reference reading gives you a general indication on whether the material is high or low in moisture. Second, you can make a more specific assessment of a particular building material by testing a piece of the same material that is known to be dry and comparing the readings.
The reference scale is generally used to measure non-wood materials.
The Drywall Scale
With most moisture meters, drywall is measured using the reference scale and comparisons to dry materials. However, Delmhorst offers several moisture meters that are calibrated specifically for drywall.
Whatever the building material you’re working with, moisture meters offer an efficient, cost-effective way to ensure that the materials are dry enough to work with and to identify trouble spots. However, understanding the different scales and the need to use the right meter and the appropriate scale is critical to effective use.
For more information about the various applications for pin and pinless moisture meters, or to find out the benefits of moisture meters for your projects, contact us now.
If you want to see the different types of moisture meters available, check out our solutions page.
