6 Hazards That Impact Moisture Meter Readings

Cob plaster kevin RF

Wouldn’t it be wonderful if when you arrived at the site of a moisture inspection, everything was ready for you? There’d be no obstructions. Areas impacted by excessive moisture would be immediately apparent. And you wouldn’t have to work too hard to take moisture meter readings. 

Unfortunately, that’s rarely the case. 

A moisture inspection doesn’t happen in a vacuum. In other words, you never walk into a controlled environment to complete a moisture survey as part of a home inspection or after a flood damage event. Impediments are likely – both seen and unseen – that if not prepared for can ruin an inspection and its results. 

For surveyors of all experience levels, knowing what to look for in both the inspection environment and a professional moisture meter’s readings makes for a more accurate final report. 


6 Impediments to Accurate Moisture Meter Readings

The last thing any inspector wants is to have the integrity of a moisture survey and its results questioned. Taking accurate moisture survey readings does take some skill, as there are some hazards that even the best professional moisture meters can’t overcome. 

When completing a moisture inspection, be mindful of: 

  1. Metal
  2. Salt 
  3. An uncalibrated moisture meter
  4. Temperature
  5. Surface-level condensation
  6. User ignorance


1. Metal

In moisture surveys, metal is a moisture meter’s worst enemy. Conductive and all throughout a building or space (especially in the places you can’t see) contact with metal makes for moisture meter false readings. Areas that are actually dry will seem incredibly moist. 

Despite its prevalence in a space (screws, nails, pipes, ducts, drywall mesh, etc.), it’s not hard to troubleshoot when a meter’s measurements are skewed by metal. When a meter comes in contact with metal, the readings will spike to the top of the scale. While investigating further in the immediate area around the metal, readings will drop off sharply and abruptly once the meter no longer making contact. 


2. Salt

Where there’s moisture, there’s probably salt. A naturally occurring substance that presents itself on damp materials – typically as a buildup (efflorescence) salt poses a few unique challenges to moisture meters

Not only does salt increase a material’s water retention, but it also makes water more conductive. During a reading with a pin-type meter (which measures moisture by measuring the electrical resistance between its probes), the presence of salt makes a material seem more inundated by moisture than it is. 


3. An Uncalibrated Moisture Meter  

With a professional moisture meter, this issue is rare. However, every so often it’s a good idea to calibrate your meter. A reset of sorts, calibration makes sure the device is taking accurate readings. 

Meters left uncalibrated during their lifetime can take measurements that are questionable at best. 

Resource: How do you calibrate a moisture meter? It’s easy and takes a few seconds. Find out here. 


4. Temperature

For all-in-one moisture meters, unregulated temperature has potential negative impacts on readings. 

All-in-one meters have the functionality of a hygrometer, pin-type, and pinless moisture meter. When in hygrometer mode, the temperature is measured when taking readings for humidity and grains-per-pound. Sudden changes in temperature – say, by an open window or a heater kicking on – throw the readings for ambient moisture presence in a space. So does a drastic difference between the temperature of the meter and the space it’s testing. A meter that’s left outside in a vehicle and exposed to temperature extremes should be given time to reach room temperature before use.  


5. Surface-Level Condensation

Typically a byproduct of temperature differences between a material and a space’s ambient conditions, condensation may give meters the wrong impression about moisture. For some pin-type meters, condensation will give high readings. Non-invasive moisture meters meter will show there’s less moisture present within its depth of measurement. 

A visual inspection goes a long way to identify surface condensation and take steps to avoid it during a moisture survey. 


Did You Know Our Moisture Meters are Unaffected by Surface-Level Condensation?

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6. User Ignorance

One of the easiest ways to take poor measurements is improperly using your moisture meter in the first place. To an extent, reading the manual matters

For instance, did you know not all non-invasive meters take readings through vinyl? Or that you’ll never get an accurate reading with a pin-type meter if its probes are forced beneath the surface of the material being tested, such as when you're taking moisture meter readings for drywall? 

Understanding how to use a moisture meter is the first step toward getting measurements you can feel confident about. 

Taking Unquestionable Moisture Meter Readings 

One of the biggest components of completing a survey is to understand moisture meter readings, what is normal, and (most importantly) when something is off. To the untrained eye, hazards impacting moisture meter readings might not always seem apparent. 

With a professional moisture meter and an understanding of its functionality, metals, salts, and user error won’t be a major concern for collecting readings and compiling a comprehensive final report. 


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