How to Use a Damp Meter for Thorough Surveys

damp meter and inspector

When it comes to completing a building survey for dampness, there's one element that matters more than anything else: thoroughness.

A survey that is ... surface level and leaves many areas under-investigated is of little use. Not only does it provide an inaccurate representation of dampness in a building or space, but it also leaves the doors open for damp issues to become much bigger and more costly to rectify.

Being thorough isn't strictly about taking as many readings as possible while surveying. 

Certainly, there's nothing wrong with an abundance of measurements – in fact, some professionals say the more readings, the better.

However, the key to being thorough and having a complete understanding of damp intrusion is using the right tools for the job. Undoubtedly, that starts and stops with knowing how to use the damp meters in your repertoire.


How to Use a Damp Meter | Pin-Type & Pinless

In completing building damp surveys, your meter options are simple – use a pin-type meter or a pinless (non-invasive) meter, or a dual-function meter (which is a combination of both). Let's take a look at each meter's function and how to best use both.

Surveying With a Pin-Type Damp Meter

New call-to-actionAs their name indicates, pin-type meters use two probes (pins) to determine actual moisture content within a material. Measuring the electrical resistance between its pins, meter readings identify the damp presence as a percentage. When more dampness is present in a material, there's less resistance between the pins as water is conductive, giving a higher reading.

Testing with a pin meter involves simply touching the meter's probes to the surface of the material being tested, waiting a second for a measurement, and recording the reading. For good measure, it's recommended to take several readings to verify results.

Surveying with a Pinless Damp Meter

Pinless meters, also referred to as "non-penetrating meters," provide a different type of reading.

Unlike a pin-type meter, a pinless meter uses radio frequencies or the capacitance of a material to assess the average dampness within its depth of measurement. Pinless meter readings help confirm the presence of dampness within an area – particularly those that can't be tested with a pin-type meter, such as subflooring covered by linoleum or behind a tiled wall.

Testing with a pinless meter involves putting the meter's contact plate to the area being tested and waiting a few seconds for it to take a reading. Pinless meters typically display readings using a color-coded scale – with a high concentration of dampness coming in red. Dry readings come in green.

Surveying with Both Meter Types

Despite their differences in how they quantify and qualify dampness, both damp test meter types work well in tandem, helping a surveyor to complete a thorough investigation.

After completing an initial visual inspection, a pinless meter helps you quickly identify areas of concern that can be investigated further with a pinless meter.

Using both meters together – or a dual-function meter – gives you an accurate and comprehensive overview of the area being inspected. This, in turn, helps the property owner to make informed decisions when it comes to damp-proofing and rectifying any problems found before they get worse. What's more, if an insurance company is involved, the more readings you can provide, the better. The last thing any surveyor wants is to have to redo an inspection to satisfy an insurer.


Digital Hygrometers & Thermal Imaging Cameras for Surveys

To our last point about gathering as much information as possible, there are two other devices that provide additional means to take a full assessment of dampness in a space.

Digital Hygrometer

Digital hygrometers take damp readings in a different direction.

Unlike a pin-type or pinless meter, which both focus on materials and locating excessive dampness, a hygrometer is used to assess a space's ambient environment. In a sense, a hygrometer provides a 10,000-foot view of dampness in a building.

Best moisture meter for concreteMeasuring relative humidity (Rh), temperature, and dew point, a hygrometer allows surveyors to examine the air inside a space to asses the surfaces that are likely at dewpoint and causing condensation. Suffice it to say, areas with higher hygrometer measurements are more likely to be where dampness is present.

However, even an accurate hygrometer's readings are not enough on their own to confirm a damp issue. Just like measurements taken by a non-invasive meter, a hygrometer's readings merit further investigation.

Thermal Imaging Camera

In a sense, a thermal imaging camera provides a means to conduct a visual inspection for that which cannot be seen by the naked eye.

Displaying a visual representation of temperature differences, a thermal imaging camera highlights areas that require further investigation as it helps to identify damp pockets in a building or material. Outside of a hot water leak, areas affected by excessive dampness appear cooler – or blue – in a thermal camera's display screen.

While a thermal camera's findings are by no means confirmation of damp presence, they do help point your survey in the right direction.

Damp Meter Do’s & Don’t’s

When it comes to using a damp meter, there are certain practices that should be followed and others that should be avoided. These damp meters do's and don'ts are essential for taking readings right the first time:


  1. Inspect the meter before each survey. Look for obvious damages, check its battery levels, and make sure you’re adequately stocked on replacement components such as pins and probes.
  2. For pinless meters, use a quick check device to make sure it's calibrated. If it’s been a few months since your last calibration, it’s time to do one – it only takes a few seconds! 
  3. Take multiple measurements of the same material & average the results. 
  4. Complete a visual inspection of a space first, looking for other signs of dampness issues, such as staining, mold, mildew, or condensation.  
  5. Test everywhere in a space.
  6. Take pictures of areas of interest with the meter displaying reading.


  1. When using a pin-type meter, don’t push its pins in too deep into the surface of the material being tested. To get the best damp meter measurements, the pins need to simply make contact with the subsurface.
  2. Don’t use your meter immediately if it was exposed to extreme temperatures (for instance, you left the meter in a hot car). The results will be inaccurate until it reaches the same temperature as the ambient environment.  
  3. Don't leave your meter unprotected when not in use. Keep it in a protective case.
  4. Don't forget a spare set of batteries when heading out to a job. 
  5. Don't forget about hazards that affect moisture meter readings, such as metals and salts.



Surveying with Complete Confidence

Regardless of the reason for an investigation – be it a water damage event or a routine inspection – damp surveys are complex and take time.

However, with a complete understanding of the damp meters you'll use, you'll have no problem correctly and thoroughly investigate any potential damp issues in a building.

What Else Do You Need to Know About Surveying a Building?

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How to Measure Moisture in Buildings - Protimeter