Consider this scenario: you’re inspecting a home and come across a potential moisture problem in a newly finished basement. The drywall feels damp, some areas of the exposed concrete floor appear darker, and there’s a noticeable musty odor. This could be a serious issue.
You reach for your moisture meter but have two options: pin vs. pinless moisture meters. Which one do you choose?
Home inspectors regularly face this type of decision – making a careful choice about the tools they use.
While both meters are designed to survey moisture, choosing between a pinless (non-invasive) or pin-type moisture meter can make a big difference in how you’ll locate and evaluate dampness.
How Pinless Moisture Meters & Pin-Type Meters Work
While both devices detect moisture, the way in which each functions impacts data collected and the depth of an inspection.
Pinless Moisture Meters
As it sounds, a pinless moisture meter doesn’t use probes (pins) to take moisture readings. Rather, these non-invasive meters detect moisture using conductance by either radio frequency or capacitance of a material. Its readings are helpful for quickly determining moisture presence in a space. They should be further investigated and confirmed by taking measurements with a pin-type meter. A pinless meter is ideal for taking measurements in places not easily accessible, such as beneath flooring or behind tile.
Pin-type Moisture Meters
Taking moisture inspections in a different direction, pin-type moisture meters provide data on the exact amount of moisture content in wood or the WME in other building materials. The distinguishing feature of a pin moisture meter is its pins, or electrodes. Inserted just beneath the surface of material being investigated for moisture, a pin meter reads actual moisture content – or wood moisture equivalent – by measuring electrical resistance between the probes. Since water is conductive, less resistance indicates a higher moisture content percentage.
6 Factors for Evaluating Pin Vs. Pinless Moisture Meters
How do you choose between using a pin vs. pinless moisture meter for a job? Here are six key factors to consider when evaluating both types of damp testing equipment:
- Surface damage
- Accuracy
- Speed
- Adaptability
- Repeatability
- Readings reportability
1. Surface Damage
Non-penetrating moisture meters don’t damage a surface, unlike pin-type meters. To be sure, while pin-type meters do leave a small mark on materials like hardwoods, plaster, or concrete, the damage is minimal and hardly noticeable.
2. Speed
Non-invasive meters allow for faster readings since they don’t require having probes make contact with the surface of the material being tested. This efficiency lets inspectors cover more area and take additional moisture measurements. If higher moisture levels are detected, a pin moisture meter can be used for confirmation.
Additionally, taking more readings quickly at the start of a survey helps pinpoint the source of moisture, allowing you to focus your inspection on the most critical areas later.
3. Accuracy
While pin-type moisture meters may not be as fast, they excel in accuracy. Compared to pinless meters, pin-type meters deliver more reliable data. When properly calibrated and with pins correctly inserted into a material’s surface, pin-type meters offer a clearer view of moisture content.
This doesn’t mean non-invasive meters are inaccurate; they are designed to detect the presence of moisture. Their readings serve a different purpose and should be understood as such. Pin-type meters can confirm and quantify the moisture levels indicated by a pinless meter. 
4. Adaptability
In a sense, pin-type moisture meters are a Swiss Army knife of sorts. Most pin meters feature removable electrodes that can be swapped for other accessories that are handy for inspections.
Common attachments include:
- Hammer electrodes
- Deep wall probes
- Extension probes
- Baseboard probes
5. Repeatability
To feel confident in a moisture content reading, additional verification might be needed. A pin-type meter lets you test the same material multiple times and consistently get the same result.
Non-invasive meters are used to take multiple readings in an area but do not assess a material in the same way as pin-type meters. They help locate moisture rather than measure its actual content.
6. Readings Reportability
When presenting the results of a home moisture survey, the parties responsible for repairs (homeowners and possibly insurance companies) are primarily concerned with the damage caused by moisture.
Pin-type meter readings indicate whether there is enough moisture to cause decay or mold, using a more detailed measurement scale compared to non-invasive meters. These readings provide a precise quantification of moisture levels in a material.
While pinless meter readings are also valuable, they mainly demonstrate your efforts to locate the moisture source during the inspection.
Further Reading: What to Include in Your Flood Damage Report
False Positive Readings
It's important to note that a non-invasive meter might detect conductive materials like metal behind the surface. Always use a pin meter on the surface to confirm whether you’re detecting moisture or metal, such as in corner beading in drywall construction.
Pin vs. Pinless Moisture Meters: Why Not Both?
Back to our original scenario.
When choosing between pin vs. pinless moisture meters for an inspection, what do you do? The answer is simple: take both.
With both meter types in your tool kit, you’ll have the equipment to provide an accurate and representative portrait of moisture presence within a material and space. Both meter types work hand-in-hand in taking complete moisture surveys.
How do the performance and reliability of pinless and pin-type moisture meters compare when used in different building materials, such as wood versus concrete?
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Find Moisture Meters That Meet Your Needs!
Or check out the Protimeter Surveymaster -- the de facto standard in restoration and inspection as it incorporates both pin and pinless measurement in one handy moisture meter.