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To get consistent results with wood, the moisture content must be reasonably low. If the wood is too wet, it will start to shrink when it dries up. And as wood shrinks, it may warp, twist, or develop cracks. In some cases, the wood may split apart, compromising the integrity of your wood project.
A wood structure made with wet lumber may bend out of shape when the wood shrinks after losing excess water. Sometimes it can be so bad that you may have to redo your project.
You can prevent this from happening to your wood projects by checking how wet the timber or lumber is before using or buying it.
Similarly, water saturation in existing wood structures is not good either. As you know, water accelerates the rotting of wood. Even treated hardwood can only keep away water for so long before it starts to draw in water and deteriorate.
Excessive water can also damage other building materials including concrete walls, drywall, cardboard, etc. And if they are painted, you will know there is excess water because the paint will start to peel off.
It is also not good to cut very wet lumber with a saw blade or put it through a planer, jointer, or sander. You will not only risk destroying the tool or the blade but also increase the likelihood of a kickback hazard occurring.
On table saws with advanced safety features such as the SawStop, wet lumber can falsely trigger the electric brake mechanism and cause the saw to shut off. This can be frustrating and you can only prevent it either by using dry lumber or bypassing the safety feature, altogether.
Why check wood MC?
Therefore it is good practice to check moisture content in wood before using it. It is also a good routine practice to check the moisture level in your finished wood projects to detect potential water leakages or high relative humidity.
If you have worked with wood for a long time, you probably know that wood is hygroscopic. It can absorb or lose water to the atmosphere depending on the relative humidity versus the wood moisture content in relation to the ambient temperature.
If the temperature is kept at a constant and relative humidity increases, wood will absorb moisture from the atmosphere until an equilibrium is reached. Similarly, if humidity is relative humidity decreases and temperature increases, wood will lose moisture in the atmosphere.
Thus, it is important to maintain the ambient temperature and relative humidity at equilibrium to prevent the wood from gaining or losing water once it is dried. This will prevent moisture problems in wood.
And there is no better way to tell the MC of wood or building material without a moisture meter.
Wood moisture meter, what is it?
A wood moisture meter is a device for measuring and monitoring the moisture content of wood. This little electronic device helps you determine the percentage of water in wood so you can decide if the wood is dry enough for use.
It is an important little device any woodworker should keep in the toolbox. Even a homeowner needs a wood moisture content tester.
You can use it to check the water content of firewood that is advertised as seasoned to see if it is indeed ready for the wood stove. The ideal moisture content for firewood that is ready to burn is anything less than 20%.
Another way a homeowner can use a wood moisture content meter is to check the wood flooring for water damage, especially when the wood flooring starts to peak strangely.
I remember the last wood flooring project I did was at my neighbor’s house. The hardwood floor in his living room and dining room had started to peak, suggesting potential water damage. To confirm that indeed the floor was water-logged, he stuck a wood moisture meter to the affected part and the moisture reading was very high. Partial removal of the floor to establish the source of the dampness revealed that a water barrier had not been installed. So he decided to redo the whole floor.
A moisture content meter can also help you find damp spots on many other surfaces including, walls, paneling, gypsum boards, and plywood walls. Experts also use the device to find roof leaks and pipe leaks.
Types of wood moisture meters
There are two main types of wood humidity meters. A destructive type or a non-destructive type.
Pin-type/destructive/invasive
A destructive (pin-type) wood moisture meter has sharp little probes that penetrate the surface of the building material to measure the moisture content. The pins poke holes into the surface and can leave visible marks on your beautiful wood. This is why pinned wood moisture meters are called destructive.
Pinless/non-destructive/non-invasive
On the other hand, a non-destructive or pinless wood moisture tester uses wireless technology to measure the moisture level in wood or any building material. It does not damage the surface of your material. And this makes it a good option for measuring moisture on painted surfaces such as drywall and concrete and any hard surface that may be difficult to penetrate.
If you ever deal with wood that has been exposed to surface moisture such as rain, a pin meter is the best measurement tool because its readings are not skewed by this factor.
What to look for in a wood moisture meter
Wood moisture meters come in different designs and some have numerous features. But these are the most critical features to look for when you go shopping for the best moisture content tester.
Accuracy
Accuracy is the most important feature of a wood moisture meter. If your meter is not accurate, it means you will get false readings that could cause you to make the wrong decisions.
The accuracy of a wood moisture gauge is expressed as a margin of error. The error should not exceed 5% of the actual reading for a good meter. However, the best wood moisture meters have an accuracy of 0.5% of the actual reading. But anything less than 2% is great!
Depth of reading
The second most important feature of a moisture content meter is the depth of measurement. This determines how deep the meter can read into the material.
Some humidity meters have different depths of measurement for various building materials. This depth of measurement is a significant limitation for non-invasive wood moisture gauges because they use electromagnetic force (EMF) to measure moisture content. And as you know, the penetration of EMF signals in solid barriers is limited.
For destructive types of moisture meters, the depth of reading is largely determined by how deep the pins can go into the wood or material. If you need to measure the MC of thick lumber, you should drive the pins deeper.
Moisture measurement range
The third important feature to consider when selecting a wood moisture content monitor is the moisture measurement range. The typical water content of good wood falls between 5% to 30%.
5-6% is the lowest MC for wood that is not overdried. Above 30% MC indicates over-saturated wood. Because you want to detect both extremes of moisture content, you should get a wood moisture meter that offers a wide measuring range. Read more about wood moisture content in this white paper.
Ease of use
When all is said and done, you want a device that you can use with ease. Therefore, a good moisture meter for wood should be simple, easy to operate, and easy to read.
Some of the qualities of an easy-to-use device are well-labeled buttons, an easy-to-read screen, and appropriate user-interface features such as audible and/or visual alerts for various wood moisture content ranges.
Also, the device should comfortably fit in the hand and you should not need to use both hands to operate it.
Extra Features
Lastly, a device with extra features from the ordinary stands out. A wood moisture meter with additional features such as a backlit screen and data storage will stand out from ordinary tools. Although the extra features are not mandatory, they add value to a tool.
5 Best Wood Moisture Meters
Tavool Wood Moisture Meter (MT270Y) – Best value for money
Tavool is one of the least expensive digital wood moisture meters but is very reliable. It is small enough to fit comfortably in an average hand and has a good variety of settings to get the most accurate readings from different materials.
The most outstanding feature of the Tavool moisture meter is the big readout screen that is easy to read. It displays large numbers that you can read from a distance. This unit also displays additional parameters besides the MC reading.
The screen has a backlight to enable you to use the tool even in dark spaces such as in the ceiling when checking for roof leaks.
The Tavool moisture gauge has two modes of operation: wood mode and building material. The measurement range for wood is 6% – 60% and 0 – 40% for building materials.
The meter has an accuracy of 2% of the actual reading and offers up to 8 calibration scales for various categories of wood. You can easily cycle through the categories using the arrow button to select the most appropriate scale for the type of wood you want to measure.
These are the categories:
Calibration scales of Tavool moisture sensor
- A: Teak, Walnut, Afrormosia, Rubber Tree Imbuia, Kokrodua, Niove Bidinkala, Cork, White Oak, Red Oak, and most hardwood
- B: Keruing, White Poplar, Beech, Cedar, Tola
- C: Lauan, Ash, Elm, Fir, Maple, Padauk Oak
- D: Basswood, Larch, Pine, Birch
- E: Abura,Bitterwood, Cordia, Erimado, etc.
- F: Amboyna, Basswood, coachwood, etc
- G: Gequ, Nohor, Rubberwood, etc
- H: Cherry, Agba, Birch, Cedar, etc.
Besides measuring the moisture content of wood, you can use the Tavool moisture content tester to measure the water content in other building materials. This is a perfect tool for finding a leak in the house either from the roof, on the wall, or underground.
Another useful feature of the Tavool MT270Y is the memory function that allows the device to store MC data for review. From the stored data, the meter calculates the minimum and maximum readings to give your an overview of the dryness range of your cache of wood.
The only thing I don’t like about this tool is the lack of additional moisture content alerts. On this tool, you only have the display screen while other meters incorporate audio alerts and haptic feedback for different moisture content levels.
Given the price point, accuracy, and ease of use, the Tavool MT270Y wood moisture checker is an excellent choice for a homeowner for testing firewood moisture and checking for leaks around the house. You can use it on wood flooring, drywall, or ceiling. This meter is also a nice choice for a DIY carpenter for checking the moisture content of lumber for making furniture.
General Tools MMD4E Digital Moisture Meter – Best for firewood
This is another simple inexpensive digital moisture meter for wood. It is designed to do one thing – measure moisture content – and it does it perfectly.
The General Tools MMD4E has a small LCD screen that only displays the MC readings. Unlike the Tavool, this unit doesn’t display other parameters on the screen. However, it has additional LED lights for indicating the moisture content range. Green for low MC, Yellow for medium MC, and red for high water content.
The device also has a beeping tone for each moisture content range. These extra moisture content alerts make for quick checking of moisture level in materials even in low light or odd angles.
The General Tools MMD4E moisture sensor has two modes of operation. Wood mode (for different types of wood) and building mode (for building materials such as concrete, plaster walls, drywall, carpet, and sheetrock). The measuring range for wood is 5% to 50% and for building materials is 1.5% – 33%. The accuracy of the sensor is 2% of the actual reading.
Unfortunately, this device does not have many features. It does not even have a memory function for storing readings. So, if you need to store the values, will need to record them manually on a piece of paper.
The pins are also quite delicate. You need to take care of them because when you break them, you will not get a replacement tool. Too bad the 1-year warranty does not cover the pins.
So if all you want is a tool that will tell you how wet or dry your lumber or firewood is, this little moisture detector will do the job effectively. It might even be a better option for doing home inspections to detect leaks in crawl spaces. The audible alerts make it so easy. This is also a perfect moisture content scanner for anyone who cannot read figures on the screen.
Klein Tools ET140 Moisture Meter – Best for DIY Woodworking
Pin-type wood moisture meters are delicate. You have to be careful not to break the pins as you puncture the surface. Also, they are destructive but quite accurate.
Klein Tools ET140 is the opposite. This is a pinless moisture detector for wood and building material. It uses wireless technology to detect the moisture content of wood and other building material.
Unlike a pin-type moisture detector, Klein ET140 is non-destructive. It works by placing it on the surface you want to measure and it will send electromagnetic field (EMF) signals into the material. The signals go as deep as 19mm, which means you cannot use this device to check the humidity levels in thicker materials.
When testing the Klein ET140 moisture detector, I liked its ruggedness. A drop from the workbench to the floor did not cause any significant damage apart from minor scratches on the plastic cover.
I don’t like that Klein Tools used a plastic cover on this meter instead of a rubber overmold. Rubber has better impact resistance and provides better grip.
Another thing I liked is the fact that this unit provides 4 different operation modes that you can toggle through easily with the mode button. These modes are drywall, hardwood, masonry, and softwood. Each mode has a unique moisture detection range but masonry and drywall have a relative range that is quite ambiguous.
Moisture detection ranges
- Hardwood: 0 – 35%
- Softwood: 0 – 55%
- Drywall: 0 – 100%
- Masonry: 0 – 100%
However, the accuracy of the meter is not that great (4%). But isn’t it obvious that non-invasive wood moisture meters are not the most accurate? These devices rely on remote sensing. They do not get into actual contact with the wood fibers.
Also, the EMF sensor on the ET140 needs to be placed on a flat surface for it to work. If the surface is not flat, you will overload the meter and you won’t get results. This makes the meter unsuitable for testing firewood.
Otherwise, if are looking for a meter that will quickly test moisture content on flat surfaces such as wood flooring or drywall without leaving poke marks, the Klein ET140 is an excellent choice. It is nicely built, easy to use, and has a backlit LCD display that you can read even in dark places.
In addition, this unit has an LED bar that lights different colors to show moisture content from dry to wet. The bar has three sections; green, yellow, and red. Green indicates low MC, yellow indicates medium MC, and red indicates high MC. There is also an audible tone that beeps to alert you when the moisture content of the material is high.
Delmhorst Wood Moisture Meter J-2000 – Best professional pin moisture detector
The Delmhorst J-2000 is one of the best professional pin-type wood moisture meters on the market. It is the perfect moisture content meter for lumber yards, wood mills, and craft shops. It also serves as a reliable quality control tool for various woodworking applications such as hardwood flooring, cabinet making, and carpentry.
This digital wood moisture tester from Delmhorst is designed for wood only. It offers a measurement range of 6% – 40% and a measuring depth of 1-1/16″. It comes with up to 48 calibrations for 48 different tree species. Each hardcoded species has a custom measurement range to account for the different electrical properties of each tree.
A nice thing about the Delmhorst J-2000 wood moisture sensor is that it allows for temperature correction of moisture content readings. If the temperature of the wood is outside the range of 50 F – 90 F, you can use the temperature button to set the temperature. This allows you to get accurate, temperature-corrected readings all the time.
And like other digital wood moisture readers, Delmhorst J-2000 features a digital readout screen. However, the screen is small and only displays moisture content readings. What’s even worse is that the screen is not backlit. This limits the usefulness of the tool in poorly lit spaces or at night.
That being said, this device can store up to 100 readings and can calculate the average and maximum readings from the accumulated values.
Lastly, this unit is simple, easy to use, and very accurate. It comes with a carry case and an extra pair of pins. Its price, however, is prohibitive for a homeowner or DIYer. This device is suitable for professional woodworkers and quality control inspectors.
Wagner Meters Orion 950 Moisture Meter – Best pinless moisture meter
The Orion moisture meter 950 is crème de la crème of wood moisture meters. It is also the top of the line in Wagner Meters moisture content scanners.
This device uses advanced technologies to measure, store, and transmit moisture content data. It logs up to 100 readings and can compute the average MC of the stored values. It also allows you to retrieve the minimum and maximum readings.
The most outstanding feature of the Orion 950 is the ability to connect to a smartphone or tablet via Bluetooth. And through Apps like Woodshop MC and Floor Smart, you can read moisture data from the device or download them for further analysis.
Another thing I like about the Wagner 950 is that it is pinless. So, it is prompt and you don’t have to worry about breaking any pins.
This device is also accurate and programmable. You can set the calibration mode out of the options provided in the user manual. You can also select the depth of measurement between 1/4″ and 3/4″. A 1/4″ depth is the appropriate setting for measuring the moisture content in thin materials.
This meter also allows you to set an audible alert when a specific moisture content value is reached. I found this feature extremely useful for scanning across walls and wood flooring to detect dampness.
Lastly, the Orion 950 is backed with a 7-year warranty. I have not come across any other wood moisture meter that offers better warranty coverage.
The major downside of this tool is the prohibitive price. It is definitely one of the most expensive handheld moisture meters for wood. It is also disappointing that the LCD screen of such an expensive meter does not light up. This can be frustrating when checking lumber moisture content in a poorly illuminated kiln.
That being said, the Wagner Orion 950 is by far the most rugged, versatile, and best-quality moisture tester in our collection of some of the best wood moisture content meters on the market. It is a great moisture meter to keep in a sawmill or woodshop. Professional woodworkers and home repairers might also find it to be a nice addition to the toolbox.
Conclusion
In summary, a portable wood moisture meter is a handy little device for checking if the wood is dry enough for use. Whether it is for making furniture, laying on the floor, or for making frames, wood must attain the correct dryness before use if you want good results. Otherwise, if you build something with wet wood it will deteriorate once the wood loses moisture. Even wood for burning should be well-dried for it to burn properly in the furnace. And there is no better way to accurately tell if the wood is dry enough except with a wood moisture meter.
A wood moisture detector is also useful on raw wood but also on finished structures. You can use it to detect dampness and leakages. Because dry wood absorbs moisture, it is good to keep checking the moisture level in your furniture so that you would know when to turn on the dehumidifier or lower/increase ambient temperature.
Lastly, most mositure meters for wood can also detect humidity levels on other surfaces such as drywall, gypsum, and concrete other than wood. You can use them to detect leakages around the house from the plumbing, roof, or from underground seepage. In short, a wood moisture meter (pinned or pinless) is a must-have tool for everyone.
