Moisture Meter Buying Guide
Moisture is a natural variable which affects numerous industries and occurs in many different types of materials. A Moisture Meter is an essential tool because it allows you to precisely quantify the level of moisture in a material you are working with. Excessive moisture can cause big problems down the line which can be costly to repair - if left unmonitored, moisture can cause dangerous mold growth, flooring failures, inventory product losses, and even professional liability issues.
Regardless of the material being measured or type of moisture meter used, the primary measurement for these tools is moisture content (MC). This measurement is often restricted to a particular scale. Measuring moisture in wood is very common – a typical scale range for a wood moisture meter is 7-20% MC, meaning the meter can detect moisture content from 7 to 20 percent in a piece of wood. Different meters will have different scales for different applications and materials.
Pin-Type
A pin-style moisture meter typically has a pair of metal probes or pins that penetrate below the material’s surface to read the moisture content. Overall, this method is more accurate than pinless measurement. Pin-type meters measure using an electric current – the current is sent between the two pins and the meter can tell how much water is in the material by how much current travels between the pins. Due to this measurement principle, testing a small area with a pin-type meter won’t give an accurate reading for the entire piece of material. Taking several readings along the full width and length of your material is recommended.
For applications like woodworking, you might think a meter like this would damage the surface of your wood – however, measurement pins are typically extremely small. Unless you were looking for the pin holes, you likely would not notice them. An advantage of these meters for woodworking applications is that you can easily use the small pins to take readings on any wood no matter what the shape, size or degree of roughness.
Another thing to keep in mind with pin-type meters for wood is that uninsulated pins will measure the wettest layer of wood they come in contact with, regardless of how deep the pins penetrate the material. This can throw off your readings if the outer layer of the wood is especially moist. Meters with insulated pins are available to get around this – these pins only measure the MC of the wood at the pin tips.
Pinless
A pinless moisture meter provides a non-destructive, non-invasive method for measuring moisture content. That said, this method is slightly less accurate than pin-type measurement with additional variables to take into account. A pinless meter will have a sensor pad on the device for taking readings. This sensor projects an electrical field into the material - the meter can sense changes in the field caused by moisture, then converts the change to a moisture content reading.
While this method provides a faster and less destructive way to measure the MC of a large piece of material, it does require that the sensor pad be in good contact with the material for accurate readings. For woodworking, this can sometimes be a frustrating issue to deal with if your wood is not perfectly flat. You must also be able to hold the sensor to a large enough area of the wood – most pinless meters have sensors that are too big to read the edge of a 4/4 board.
One other issue to keep in mind with pinless moisture meters is that these tools can give incorrect readings if influenced by surface-level moisture. In some cases, the reading that the device gives you may be reflective of moisture build-up on the surface rather than the interior of the material.
Wood
Moisture measurement is extremely common when working with wood. Meters for this application can be either pin-type or pinless. An important feature to consider with moisture meters designed for use on wood is the measurement range of the meter. As mentioned above, a typical scale range for a wood moisture meter is 7-20% MC. For certain applications like woodworking and furniture manufacturing, you will want to make sure your meter can measure on the low end of the scale (around 5%). Make sure to check what scale range you need before making a purchase.
Another consideration which is unique to wood moisture meters is species and temperature correction. Temperature and wood density can influence the readings given by your moisture meter, causing inaccurate measurements. To address this, most manufacturers include charts to guide you when adjusting for specific species and temperature variations. This is especially true for pin-type meters since these tools are more sensitive to temperature variations than pinless meters. Higher-end pinless meters will have built-in species correction and possibly built-in temperature correction as well.
If you plan to use a pin-type moisture meter for a woodworking application, keep in mind this rule of thumb for measuring MC in wood with a pin-type meter - the average MC of a board can be found at a depth equal to 1/5 to 1/4 the thickness of the board. Following this rule, a 1-1/2-inch thick board will require pins that are at least 5/16-inches in length.
Building Materials
Moisture meters designed for testing building materials will often be able to test multiple materials. These materials can include sheetrock, ceramic tile, plaster, linoleum, mortar, brick, and more. As with wood moisture meters, these meters will have specific measurement scales for each type of material – be sure to check this before purchasing. These meters typically do not provide specific MC percentages as they are meant to provide only a relative MC reading for comparison purposes. This can help to identify problem areas in a building where moisture might be an issue. These meters are also available as pin-type or pinless models.
Soil/Hops
Soil moisture meters are primarily pin-type meters with a larger pin probe for reaching down into the soil. They give a measurement of the moisture content of the soil being tested. This can be an essential tool for agricultural industries and gardeners. Specialized meters for this application are also available which incorporate other measurement functions like temperature, soil Ph, and more.
Moisture meters for hops and hay also fall into this category – there are meters available to measure the moisture in stored grains like these to prevent moisture issues which can result in fungi, sprouting, and insect infestations.
Infrared
This category of moisture meter provides additional capability over standard meters by incorporating thermal imaging technology. This allows you to measure the radiant heat energy of a scene – while it won’t show moisture measurements, it will show you colder areas of a scene which could indicate water damage, mold, or other moisture-related issues. This can be very helpful to scan a large area quickly and identify any possible problem areas for deeper inspection later on.
FLIR, one of the world’s top thermal camera manufacturers, offers several thermal imaging moisture meters. Coming from FLIR, you can be confident that the thermal imaging capabilities of these tools will be unmatched. Plus, each unit also incorporates pin and pinless moisture measurement for 9 material groups so you can scan an area and do in-depth checks with only one meter.
Display Type
There are various different display types available for moisture meters. Today, options include analog, LED, digital LED and digital LCD. This is really your preference – you might find you like the operation of an analog display, or that you need features like data hold which come with many moisture meters featuring digital displays. The resolution of a digital display is also important, with higher-end meters providing smaller data increments up to 1/10 percent.