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What Are Moisture Meters?

Moisture meters are handheld devices used to determine the moisture content in a variety of materials including wood, concrete, soil, and paper. They come in two varieties, pin and pinless.

Measuring moisture content is important because moisture is related to a host of problems including flooring failures, damage to inventory, and issues revolving around liability. In short, too much — or too little — moisture can end up costing you a lot of money.

Moisture meters measure the moisture content of your materials to ensure that they’re at the proper moisture content for your needs, whatever they may be.

In this article, we’ll be taking a look at three types of moisture meters: wood, concrete, and soil. We’ll finish it up by talking about several important features to look for in a moisture meter.

Wood Moisture Meters

Pin Wood Moisture Meters

A pin moisture meter has two small pins that must physically penetrate the wood in order to take a reading. When the meter is turned on an electrical current flows between the pins and measures the resistance encountered. The drier the wood, the more resistance. This is because water (with impurities and salts) is a great conductor of electricity, while wood isn’t.

Pinless Wood Moisture Meters

A pinless moisture meter is a non-invasive moisture meter. They don’t need to penetrate the wood in order to take a moisture content reading. Instead, they use an electromagnetic moisture sensor to quickly scan the wood’s surface and accurately measure the moisture content down to .25 inch, .75 inch, or all the way down to 1.5 inches.

Obviously, since pinless meters don’t poke holes in the wood they’re great for measuring the moisture content of expensive furniture and hardwood floors.

Concrete Moisture Meters

Determining the moisture content of concrete is important if you’re going to be placing anything moisture-sensitive on top of a concrete slab. For example, too much moisture can cause changes that destroy the adhesives used in floor coverings. As these adhesives begin to breakdown your new floor will start to swell, bulge, or cup. Not a pretty sight.

In situ relative humidity (RH) tests are used to find the moisture content of a concrete slab. Sensors are inserted into the slab and after they’ve had a chance to equilibrate, an RH reading is taken. Handheld concrete moisture meters — both pin and pinless — are used to determine where to place sensors. In other words, the meters themselves don’t take the moisture reading. They only help the professional conducting the RH test find the best locations to place the sensors.

Soil Moisture Meters

Soil moisture meters measure not only the moisture content of soil but other aspects as well, including its temperature and pH level, to ensure that it can sustain the growth of both indoor and outdoor plants. There are even some special soil meters that are used for measuring the moisture content in grain stores in order to guard against moisture-related problems like fungi, insects, and sprouting.

Features of a Quality Moisture Meter

When you’re in the market for a moisture meter there are a few things you should watch out for to make sure you get the best value for your money.

Accuracy

When it comes to wood moisture meters, if you’re going to be measuring the moisture content of firewood only, you can get away with purchasing an inexpensive meter. This is because if it’s only firewood, accuracy is less important and even if your meter gives you a reading that’s several percentage points off, that’s probably OK.

However, professionals who work with wood — hardwood flooring installers, cabinet makers, etc. — need a more accurate moisture meter, one that can provide a moisture content reading that gives a reading close to the actual moisture content. Woodworking professionals also need a moisture meter that can accurately read low moisture content. Less expensive moisture meters cannot do this.

Price Range

As we mentioned above, if you’re just measuring the moisture content of firewood you probably don’t care if the meter’s accuracy is poor. Therefore, you can probably get by with an inexpensive pin-type meter in the $50 range. Pin meters are good for firewood because you don’t have the smooth surface necessary for pinless meters.

Obviously, if you’re a woodworking professional or serious hobbyist and want an extremely accurate meter you’ll need to spend more money. The inexpensive, lower end meters do not offer the kind of accuracy necessary for professional woodworkers, flooring installers, or even many hobbyists who work with wood. The prices for these meters start at around $200 and go up from there.

Learn more from our moisture meter buying guide.

Measuring Depths

Wood dries from the outside in. Therefore, wood on the inside is usually going to be wetter than wood that’s closer to the surface. For jobs where you need a high accuracy, you’ll need a meter that’s capable of taking a deep reading.

Now, you don’t need a pin meter in order to take a deep reading. A pinless moisture meter is capable of taking accurate readings deep enough for most needs including wood flooring, cabinets, etc. Pinless meters also won’t poke holes in your wood.

Taking a deep reading using a pin meter requires an external device called a hammer probe with insulated pins. (If the pins aren’t insulted the current will find the path of least resistance and follow it, wherever that may be.) Also, the pins will need to be inserted correctly for an accurate reading and this gets more difficult with longer pins.

Materials That Can Be Measured

Of course, you’ll need to buy a moisture meter designed to measure the correct material. For example, you can’t measure wood using a moisture meter for concrete, soil, or paper.

You can also buy infrared cameras that are designed to detect radiant heat. They can help you spot moisture problems via variations in temperature because moist areas are normally cooler. Building inspectors use them to spot potential problem areas in drywall that can then be scanned using other types of meters.

Durability

You don’t want to buy a meter that’s going to fall apart not long after you buy it. You want one that’s durable and can hold up under even heavy use. So, look for a sturdy case.

Ease of Use

You’ll also need to consider whether the meter you’re thinking of buying is easy to use (including easy to read) or not.

Pinless meters are both easier and quicker to use than pin meters. Because pin meters only measure the moisture content between the two pins you may need to take several meter readings and poke quite a few holes in the wood in order to get an accurate picture of its moisture content. Pinless meters, on the other hand, can scan large areas of wood in just seconds without causing any damage.

Conclusion

So, is there a best moisture meter? Well, let’s just say that whether you’re looking to measure the moisture content in wood, concrete, or soil, keep in mind that when it comes to accurate moisture readings, the quality of the meter matters.

Less expensive devices may have visible features that seem attractive such as a backlit LCD display, an audible alarm, or various buttons that light up. However, higher-end meters — a professional moisture meter, in other words — are valuable because of invisible features like accuracy, reliability, and the consistency of their readings.

In the market for the quality moisture meter? Make sure you’re an informed buyer by checking out our wood moisture meter reviews. We’ve included both the pros and cons of what we consider to be the world’s top-rated moisture meters.