Question 1

Which measuring device is suitable for wall moisture?

Accepted Answer

Both capacitive and resistance-based moisture meters are suitable for measuring wall moisture. An advantage of capacitive meters is that they penetrate several centimeters into the masonry without causing damage, allowing a large area to be examined quickly. GANN models offer particularly high measurement accuracy and device-specific professional material characteristics. The Hydromette® BL Compact B 2 and the Hydromette® Compact B evo 100 are ideal for the quick, non-destructive detection of moisture pockets in walls. For depth or layer measurements, a device based on the resistance measurement principle is preferable. The Hydromette® BL E supports resistance measurement, which - when used with the appropriate accessories - allows for the assessment of deeper material layers. At the same time, the Hydromette® BL E, for example, also offers the option of non-destructive measurement by connecting a capacitive measurement probe - making it an ideal combination device. For detailed structural analyses, the Hydromette® CH 17 is recommended, as it supports various capacitive and resistance-based measurement probes and thus precisely evaluates mineral-based building materials such as screeds, concrete, or plaster. Simple consumer-grade devices are usually sufficient only for a rough assessment, whereas professional measurement tasks require a high-quality device with reliable scaling and reproducible results.

Question 2

How does a wall moisture meter work?

Accepted Answer

A wall moisture meter operates non-destructively using the capacitive principle or minimally invasively using the resistive principle. The device generates a high-frequency electric field that penetrates several centimeters into the building material. Since water is more electrically conductive than dry plaster, masonry, or concrete, moisture alters the capacitance of this field. The device displays this change as a measurement - often in digits - on the screen. In resistance-based meters, metal pins are inserted into the material, and the electrical conductivity is measured. The conductivity of kiln dry material is very low, or the resistance is so high that no significant current can flow. The more water present, the more conductive the material becomes, or the lower the electrical resistance. Capacitive measurement is preferable for quick, non-destructive measurement of even larger areas. When in use, the device is held at a 90° angle to the wall; higher readings indicate moisture or moisture penetration. Metals in the substrate, salt-containing building materials, or dense coatings can affect the measurement, which is why it is advisable to take comparative measurements on a dry reference surface of the same wall construction. For depth or layer measurements, drill holes must be made prior to the measurement. Appropriate measures must be taken to ensure that there are no electrical wires, water pipes, or other utility lines in the vicinity of the drill holes. For damage-related analyses, professional devices are often used that detect deeper layers and provide more reliable comparative values.

Question 3

What values should a moisture meter for concrete display in digits?

Accepted Answer

Three factors are particularly crucial for evaluating the digital readings of concrete or screed: knowledge of the building material (e.g., lightweight concrete vs. normal concrete; anhydrite screed vs. cement screed), the type of installation (e.g., with reinforcement or underfloor heating), and the measurement technology used. GANN devices offer dimensionless measurement in digits for both resistance measurement and capacitive measurement. The digit values obtained using these different measurement techniques must not be compared with one another under any circumstances. In addition, GANN offers devices that cover both the 0-100 capacitive measurement range and the 0-200 measurement range. These different measurement ranges are accompanied by corresponding maximum penetration depths. For example, the measurement field of the Hydromette® Compact B evo 100 penetrates approximately 10–20 mm into the concrete, while the measurement field of the Hydromette® BL Compact B 2 can penetrate approximately 20-40 mm. Therefore, conversion between these scale ranges is not possible. Dry or standard-moisture concrete typically falls between 20 and approximately 45–55 digits (scale range 0–100) or between 30 and approximately 70–90 (scale range 0–200), while slightly elevated moisture levels are detectable between 55 and 75 digits (scale range 0–100) or 90 and 120 (scale range 0–200). Values above these ranges often indicate significant moisture penetration or a subfloor that has not yet dried out. Since “digits” do not represent percentages but rather device-specific comparative values, taking a measurement at a known dry location is helpful for reliably interpreting deviations. For binding approval decisions - such as laying flooring over the screed - CM measurement is still required; the “digit” measurement is primarily used for quick, non-destructive monitoring of moisture distribution in concrete.

Question 4

Can a wood moisture meter also be used on walls?

Accepted Answer

In general, a wood moisture meter cannot be used on walls. There are combination meters that include material characteristics for both wood and mineral building materials. Meters designed exclusively for wood are calibrated for the electrical properties of wood and therefore often provide unreliable or difficult-to-interpret readings when used on masonry.

Question 5

How accurate is a wood moisture meter?

Accepted Answer

The term “resolution” is often confused with or equated to accuracy. This is incorrect. High resolution does not automatically mean high accuracy. The accuracy of a wood moisture meter depends heavily on its design and quality. Professional devices, such as those from GANN, are equipped with a high-quality measurement amplifier and achieve accuracies of ±0.5 percentage points (Hydrometten) and ±1 percentage points (compact-class Hydrometten), depending on the measurement range. These devices thus deliver very precise results - even in the low wood moisture range, which is critical in the furniture and construction industries. Inexpensive devices from home improvement stores, on the other hand, often exhibit significant deviations and are better suited for rough estimates. In addition to the device’s technology, proper use plays a crucial role in obtaining accurate measurement results: The wood species must be set correctly, the temperature must be taken into account, and the measurement must be taken at a suitable location. In particular, measurements taken at the end grain, in cracks, or on unsplit surfaces can easily lead to inaccurate results.

Question 6

What does a wood moisture meter measure?

Accepted Answer

A wood moisture meter measures the absolute moisture content of the wood, expressed as a percentage by weight. This value indicates how much water the wood contains relative to its completely dry state. Most handheld meters operate by measuring the electrical resistance between two metal pins: The wetter the wood is, the better it conducts electricity, and the lower the measured resistance. Some devices use a capacitive method instead of resistance measurement, in which moisture is determined via an electric field without piercing the wood. For reliable results, firewood should always be measured on a freshly split inner surface, since the outer bark is often significantly drier and yields inaccurate readings.

Question 7

How does a wood moisture meter work?

Accepted Answer

A wood moisture meter works by measuring either the electrical resistance or the dielectric properties of the wood. Devices with measuring probes pass an electric current between two electrodes that are driven into the wood. Since drier wood has higher electrical resistance and moister wood conducts electricity better, the device can calculate the moisture content based on this. Capacitive meters generate an electromagnetic field and measure how it changes due to the moisture in the material - without damaging the wood at all. Both methods require the correct wood species setting, because different wood species conduct electricity to varying degrees, and failing to set this correctly can result in inaccurate readings. For years, GANN has been known for manufacturing high-quality wood moisture meters. GANN’s Hydromette BL A plus now combines the high-precision resistance measurement method with the non-destructive capacitive measurement method in a single compact device.

Question 8

What is the purpose of a wood moisture meter?

Accepted Answer

A wood moisture meter is used to reliably determine the actual moisture content of wood. This value is crucial for assessing whether firewood will burn cleanly and with low emissions, whether timber is suitable for processing, or whether wood used for furniture is sufficiently dry to prevent cracking or warping. The device thus enables a reliable assessment of wood quality before and during processing and helps prevent damage, energy loss, or malfunctions when using a fireplace. When heating, knowing the moisture content is important because wood that is too wet burns less efficiently and produces higher emissions.

Question 9

How do you use a wood moisture meter?

Accepted Answer

To use a wood moisture meter, first set the correct wood species group on the device. If the device has a wood temperature compensation feature, set that as well. Then press the measuring pins into the wood at a right angle to the grain. When measuring the moisture content of firewood, it is best to use freshly split wood to access the moister core. Since moisture levels can vary within a single piece of wood, it is advisable to take several measurements at different points and then calculate an average value. For use as firewood, the moisture content should be below 20 percent; an optimal residual moisture content is approximately 15 to 18 percent.

Question 10

How do I choose a wood moisture meter?

Accepted Answer

The choice of a wood moisture meter depends primarily on the intended use and the required accuracy. For firewood, a simple pin type meter is usually sufficient, as long as it reliably indicates whether the moisture content is below the often-recommended threshold of 20 percent. For professional use in timber construction or the furniture industry, however, high-quality meters with the appropriate accessories are necessary. That’s why GANN’s product portfolio includes a wide range of accessories for every application - from measuring firewood to determining the moisture content in sawn timber with a thickness of 20 mm or more, to measuring beams with a thickness of up to 180 mm. On the other hand, those who wish to test sensitive surfaces or veneers should choose a capacitive moisture meter, which operates in a completely non-destructive manner. Also important are material characteristics for different wood species, a sufficiently large measurement range, good resolution, and - for more demanding applications - temperature compensation, as this significantly improves accuracy.

Question 11

Which moisture meter is suitable for firewood?

Accepted Answer

A sturdy, probe-type wood moisture meter is particularly well-suited for firewood. Ideally, the wood should be freshly split before measurement, as this allows the moisture content to be determined directly at the core of the log, thereby providing the most accurate results. The probes should be able to penetrate as deeply as possible to measure the actual residual moisture content, which is crucial for clean and efficient combustion. A good meter measures in the range of 10 to 50 percent and ideally offers a wood type setting so that different types of wood can be accurately assessed. Models from GANN offer particularly reliable measurement quality and are therefore recommended for both private fireplace owners and professional users.

Question 12

Where is the best place to put a hygrometer?

Accepted Answer

Measurements taken with a hygrometer should always be made in a location that accurately reflects the actual indoor humidity. The ideal position is at a height of about 1.5 m, not directly against exterior walls, and at least one meter away from windows, doors, and radiators. Drafts or direct sunlight can significantly skew the readings. In rooms with high humidity levels - such as bathrooms, kitchens, or bedrooms - a central location is recommended so that the device can reliably detect typical humidity spikes. Even in basements or unheated rooms, hygrometer measurements should not be taken directly against cold surfaces, as condensation forms there and can cause the device to display unrealistically high readings. It is also important to allow the device to acclimate for a few minutes so that the sensor can adjust to the temperature and humidity. Devices from Gann, such as the Hydromette® BL Compact TF 3, are compact and portable, allowing measurements to be taken at various locations. Climate data loggers are available for professional use in building diagnostics.

Question 13

What humidity level does a hygrometer display?

Accepted Answer

A hygrometer measures relative humidity in percent - that is, the proportion of water vapor actually present relative to the maximum possible amount at the current temperature. In living spaces, levels between 40 and 60% are considered ideal. If the relative humidity falls below 35%, the air becomes too dry, which irritates the respiratory tract and mucous membranes. Conversely, levels above 65% increase the risk of mold, especially in poorly insulated areas. Household hygrometers typically measure in the range of about 20 to 90% RH. Professional devices provide reliable readings even beyond this range. Depending on the device, the measurement is taken either mechanically (e.g., using hair or synthetic fibers) or electronically via humidity sensors, which provide particularly fast and stable readings.

Question 14

What is the difference between a hygrometer and a hydrometer?

Accepted Answer

A hygrometer measures humidity and indicates how moist or dry the air in a room is. A hydrometer, on the other hand, is used in liquids to measure their density or specific gravity, for example in winemaking, brewing, or aquariums. A hydrometer works on the principle of buoyancy: the denser the liquid, the higher the device rises. A hygrometer, on the other hand, uses mechanical or electronic humidity sensors. Although the terms sound similar, the two instruments serve completely different purposes - air measurement versus liquid analysis.

Question 15

Are hygrometers useful?

Accepted Answer

Yes, hygrometers are extremely useful indoors because they help maintain a healthy indoor climate and detect moisture damage early on. They reliably indicate when the air is too humid - and thus promotes mold growth - or too dry - and irritates the respiratory tract, skin, and eyes. Especially in bedrooms, kitchens, bathrooms, basements, or new buildings, hygrometers provide important indications of when it’s necessary to ventilate thoroughly. This also helps prevent unnecessary heat loss. High-quality models - such as those combined with GANN measurement systems - also offer very high measurement accuracy for demanding applications. For example, the Hydromette® BL Compact TF-IR 2 enables a reliable assessment of conditions where temperatures fall below the dew point by combining surface temperature measurement via an infrared sensor with air humidity and air temperature measurements; it also allows for the detection of borderline situations on surfaces such as walls, ceilings, floors, and window and balcony door lintels.

Question 16

What is the tolerance of a hygrometer?

Accepted Answer

The tolerance of a hygrometer depends on its design. Digital hygrometers typically have an accuracy of about ±2 to ±5% RH, while analog hair- or fiber-based meters often have an accuracy of ±5 to ±10% RH. It is important to note that accuracy is often temperature-dependent and that sensors can drift over time. Deviations can occur, particularly with lower-priced models, if the device has not been calibrated for a long time or is used under extreme conditions. It is therefore recommended to check the measurement accuracy regularly.

Question 17

How do you calibrate a hygrometer?

Accepted Answer

A hygrometer can be calibrated at home using the so-called salt method. To do this, place the device in an airtight bag along with a small dish of saturated salt solution. The solution creates a constant relative humidity of 75%, which serves as a reference after several hours. It is important to always allow the hygrometer to fully acclimate to room temperature before calibration. Alternatively, calibration can also be performed using special reference solutions or by comparing measurements with a precise reference instrument. For professional calibration, specialized calibration laboratories offer various humidity points, in contrast to the single-point calibration at 75% RH mentioned above.

Question 18

Do digital hygrometers need to be calibrated?

Accepted Answer

Yes, digital hygrometers should also be calibrated regularly, as their sensors can lose accuracy due to aging, fine dust, temperature fluctuations, or prolonged storage. Although digital models are generally more stable and precise than analog hair-dryer hygrometers, it is recommended to check them once or twice a year. Calibration is particularly important for applications such as monitoring indoor air quality, preventing mold, or protecting sensitive materials. The salt method is the simplest procedure here as well. If the displayed value deviates significantly from the expected humidity level, or if high accuracy is required, the device should be checked sooner.

Question 19

How deep can a moisture meter penetrate a wall?

Accepted Answer

The penetration depth of a moisture meter depends heavily on the measurement technology used and the wall construction being examined. Capacitive devices, which operate completely non-destructively, typically detect moisture at a depth of about 20 to 40 millimeters; some professional models can even reach depths of up to 50–60 millimeters. So-called pin-type moisture meters operate on the principle of resistance measurement and penetrate as deeply as the length of the probes allows. Here, the penetration depth can be significantly increased by using professional accessories designed specifically for the measurement task. Devices from GANN offer both - non-destructive detection AND accessories for depth or layer measurements. It is important to note that metals or salts in the plaster can distort the readings - maintaining a sufficient distance from corners and metallic components improves accuracy.

Question 20

What do moisture meters display?

Accepted Answer

Moisture meters display different measurement values depending on the type of device. Many models display the material moisture content as a percentage - that is, the proportion of water contained in the material. Capacitive moisture meters, on the other hand, typically use a relative scale with so-called “digit” values, which allow for a quick assessment of moist and dry areas. Professional meters also offer material characteristic curves. Hygrometers, on the other hand, measure relative humidity and temperature, allowing for a precise assessment of the indoor climate. Here, too, professional devices stand out with additional calculations and displays of various parameters, such as dew point or absolute humidity. Compact meters for both residential and commercial use are an integral part of GANN’s product portfolio.

Question 21

Can moisture meters detect mold?

Accepted Answer

A moisture meter cannot directly detect mold, but it reliably identifies the moisture that enables mold growth. If readings in walls, ceilings, or floors are significantly elevated, or if the relative humidity in the room is consistently above about 65 percent, there is a high risk of microbial growth. Capacitive devices measure moisture to a depth of several centimeters, allowing them to reveal hidden sources of moisture. However, a microbiological test would be necessary for definitive detection. Nevertheless, moisture meters are an indispensable tool for preventing mold growth in a timely manner or for identifying the cause of existing stains. GANN’s measuring devices use a combination of ambient air measurements and infrared surface temperature measurements. This combination of measurement techniques is available either as a handy standalone device or as an active electrode for connection to multi-parameter measuring devices.

Question 22

How accurate are moisture meters?

Accepted Answer

The accuracy of a moisture meter depends largely on the measurement method and the quality of the device. So-called pin-type meters, which operate on the resistance principle, provide precise results for wood and building materials near the surface. Capacitive meters are excellent for detecting moisture distribution and comparing dry areas with damp ones, but often do not provide absolute percentage values. High-quality professional meters, on the other hand, feature adjustable material characteristics. GANN models are additionally equipped with a high-quality measurement amplifier. A wood species selection for automatic measurement correction covering over 300 wood species, temperature compensation, and wood species grouping significantly increase measurement accuracy. Inaccurate results are often caused by incorrect material settings, temperature differences, or interference from metallic components.

Question 23

What is the Hydromette® BL Compact S?

Accepted Answer

The Hydromette® BL Compact S is a compact, probe-type meter for the precise determination of moisture content in wood fuels. It features two integrated probes that use the resistance principle to take measurements at a depth of approximately 15 millimeters. The device’s built-in calibration curves for hardwood and softwood, along with the two-step wood type correction, allow for direct display of measurement values in weight percent (wt% / atro) as well as wood moisture content in % water content. A two-line LCD display and the Min, Max, and Hold functions make it easy to use. Thanks to its reliability, the BL Compact S is equally popular among both home users and professionals.

Question 24

What is the Hydromette® BL Compact B 2?

Accepted Answer

The Hydromette® BL Compact B 2 is a non-destructive building moisture indicator that uses a high-frequency spherical probe to detect moisture in walls, floors, and ceilings. The device measures to a depth of 20 to a maximum of 100 millimeters, depending on the material’s density, and is ideal for quickly visualizing moisture distribution or locating areas of high moisture concentration. In addition to a scan mode with digital readings, it also provides direct moisture readings in weight percent or CM percent. Both the material characteristics and the audible threshold alarm are individually adjustable, facilitating professional moisture assessment. The BL Compact B 2 is extremely useful both as a preliminary testing device prior to CM measurements and for quick indication.

Question 25

What is the Hydromette® BL Compact TF 3?

Accepted Answer

The Hydromette® BL Compact TF 3 is a precise thermo-hygrometer for measuring air humidity and air temperature. The plug-in TF-Stick sensor allows for flexible measurements in various locations and provides reliable readings for climate analysis in living spaces, storage areas, museums, or as part of building moisture diagnostics. In addition, the device automatically calculates key climate parameters such as the dew point, absolute humidity, and wood moisture equilibrium. The three-line display clearly shows all relevant values simultaneously, making the BL Compact TF 3 a versatile tool for assessing indoor climate and preventing mold.

Moisture Meters

GANN moisture meters provide precision for the following applications:

Wood Moisture

Structural Moisture

Air Humidity

Wood Moisture Meters

Moisture Meters for Building Moisture

Indoor Air Humidity Meters

GANN Moisture Meters - Your Benefits

Hydromette® – Meters for Experts

Quality has a name: GANN Mess- u. Regeltechnik GmbH

Frequently asked questions