Why Wood Moisture Meters Are Used for Measuring Moisture
in Other Materials

Wood has a long, long history as a building material. Next to stone, it’s what we’ve been using to construct our homes and other structures since prehistoric times. That makes sense – wood is strong, adaptable, and abundant. 

While construction methods have evolved, the same holds true for the material today. 

Even in buildings made predominantly of steel, brick, or concrete, wood still has its place in almost any structure. Just like in the earliest dwellings, wood gives spaces definition or provides structural support. 

A material that’s reactive to ambient conditions in a way that others aren’t, wood requires a bit more attention when it comes to moisture – you’ve never heard of a brick rotting. But that same reactivity makes wood a barometer of sorts for measuring moisture in other materials. 

Whether you’re completing a home inspection, checking a property after a flood damage incident, or installing new hardwood floors, having a professional moisture meter that’s calibrated for wood on hand goes a long way. 

With its readings, you’re able to make a better determination of safety, longevity, and durability of wood and many other materials in homes and other structures.

Wood & Moisture: Real-time Reactivity

Why is wood the basis for moisture meter calibration and measuring moisture in other materials? 

One of the few building materials considered organic, wood was once living. And while a piece of lumber will never grow, it does retain some of the same properties it had when living. 

Specifically, wood is hygroscopic, meaning it can absorb or release moisture. This phenomenon is ever-present as unsealed or untreated wood is always trying to be in equilibrium with its environment. That’s why on a hot, humid day, you’ll notice doors stick to their frames or even more hairline cracks in plaster walls because of wood swelling and taking in more moisture to equilibrate to ambient conditions. 

For untreated or unprotected wood, prolonged exposure to excessive moisture presents a host of problems that compromise the integrity of a piece of wood or the soundness of a structure:

• Microbial Growth: Moisture in wood creates a conducive environment for fungi and bacteria, leading to microbial growth that can rot and weaken the wood.

• Warping: When wood absorbs moisture unevenly, it causes differential expansion or contraction, resulting in warping, where the wood distorts from its original shape.

• Deterioration/Degradation: Excessive moisture accelerates the breakdown of wood fibers over time, leading to deterioration or degradation that compromises the wood's structural integrity.

• Splitting: Fluctuations in moisture content can cause wood to dry unevenly, leading to splits along the grain as the wood contracts more in some areas than others.

• Buckling: Wood floors or panels may buckle, lifting away from their underlying surface, when they absorb moisture and expand without sufficient space to accommodate the enlargement.

• Cracking: As wood dries and loses moisture, it can develop cracks due to the stress of uneven shrinkage, especially in dryer conditions.
  
  

To our original question: Why is wood the basis for moisture meter calibration and measuring moisture in other materials?

Like wood, other building materials – such as plaster, drywall, and even brick – also absorb and release moisture based on the ambient conditions of the space or contact with other materials. Using wood as the baseline for moisture measurements, the playing field between materials is equal, and it’s easier to gauge actual moisture presence. Another way, by using wood as your standard for moisture measurement, you don’t need to take and interpret different measurements for different materials and then attempt to compare them – that would take a lot of time and require having a few different devices on hand. 

Choosing the Right Meter | Pin-type Vs. Pinless

For home inspections, flood damage restoration, and flooring installation, your choice of wood moisture meter isn’t any different than what you’d choose for most other moisture surveys. 

You’d still need a professional moisture meter calibrated for wood.

And yes, there are some wood moisture meters made for more specific applications – you might come across lumber moisture meters with built-in species correction for more accuracy in specialty applications, such as woodworking. However, for general use in a moisture survey, the two standard moisture meter types every inspector should have in their toolboxes are more than sufficient: pin-type and pinless (non-invasive) moisture meters. 

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Moisture Meter for Wood & Other Materials: Meter Selection 

Like testing other materials, you’ll have two choices for your moisture meter for wood or other building materials: pin-type meters or pinless meters. Let’s look at both types. 

Pin-type Meters

This meter type is the go-to for checking wood for moisture. It also works just as well for checking plaster, drywall, & even brick. 

Why? 

Their readings provide a quantitative measurement, meaning they tell you the moisture content (as a percentage) in the wood you’re testing. With these readings, you’ll have the best idea possible about whether the wood or other material being tested has excessive moisture or is within an acceptable range. 

Pinless (Non-invasive) Meters

This meter type is less-frequently used for testing wood and other materials during inspections than its pinned counterpart. 

That’s because of the type of reading it takes. 

Non-invasive moisture meters do not measure actual moisture content; rather, they measure moisture presence within its depth through conductance measurement. Another way, pinless meters tell you if there’s moisture around, but not how much. For wood testing, this lack of specificity is helpful when trying to determine areas that require further investigation. 

What’s the Best (Wood) Moisture Meter?

One that is not only accurate and reliable, but also lightens your load. Dual-function meters, such as our SurveyMaster, can function as both a pin-type and pinless wood moisture meter.