| Objective: To substantiate that the electronic moisture meters are a
legitimate tool for detecting potential moisture problems.
Investigation:
- List Brand Names of common moisture meters with manufacturer’s
contact information.
- Delmhorst Instrument Co.: www.delmhorst.com
- GE Measurement & Sensing Technologies: www.Protimeter.com
- Wagner Electronics: www.moisturemeters.com
- Tramex Ltd.: www.tramexltd.com
- Types of Moisture Meters:
- Pinless – non-intrusive measuring.
- Pin – penetrates into softer material or only contacts surface.
- Hygrometer Probe – thermo-hygrometer attachment for intrusive testing
of ERH (equilibrium relative humidity in material) and can also measure
RH (relative humidity in air) of the local atmosphere.
- Wood Scale- calibrated for wood.
- Reference Scale – a general relative calibration.
- Gypsum Scale – calibrated for gypsum.
- Concrete Scale – calibrated for concrete, and reasonably accurate
within a certain range on some meters. It can also be used to measure relative
readings through brick, plaster, masonry, ceramic tile, and stone.
- Relative Humidity (RH) test method ASTM F-2170-02 - measures RH, temperature,
and dew point (recommendation 75% and 85% depending on permeability of
product being installed) using hygrometry instrument to store data and
download to computer for evaluation and charting.
- Data-logging with computer interface.
- Manufacturer’s recommendations for use of the moisture meter relative
to ceramic tile, stone and concrete.
- Delmhorst recommends the Accuscan Pinless electrical resistance
meter to measure moisture in concrete and tile floors with ¾” penetration.
- GE recommends the 3-in-1 Protimeter, using pinless radio frequency, to
measure to ¾” below the surface of concrete and ceramic tile.
- Tramex pinless Moisture Encounter Plus signal penetrates up to 1” into
materials being tested for most coverings such as ceramic tile and concrete.
The Tramex pin type Concrete Moisture Encounter measures electronic impedance
to a depth of ½ inch through parallel low frequency signals and
is designed and calibrated for concrete. This meter will measure moisture
content to over 6% for concrete.
- Wagner pin-free “Concrete Analog” Proline C575, uses Advanced
electromagnetic wave technology for measuring moisture ¾” down
into concrete and ceramic tile.
- List ways tool can be used for troubleshooting.
- Quantitative vs. Qualitative – Quantitative measurement
is a precise unit of measure, such as pounds per thousand square feet,
as in the Calcium Chloride Dome test, or the percent absorption, as in
the ASTM C97 stone test, or the percent water absorption, as in the ASTM
C-373 test for ceramic tile. Some moisture meters are calibrated to give
an actual moisture content reading for materials such as wood or the material’s
wood moisture equivalent (WME) value. Qualitative measurement is a measurement
using relative values that don’t represent any particular unit of
measure. For instance, the Protimeter measures up to 1000 units, and the
Manufacturer claims that a reading over 200 is considered on the high side
of moisture. The Tramex Concrete Moisture Encounter has a scale that measures
a relative reading from 0 to 100. Since the values are relative readings,
take a reading on an area that is known to be dry and then measure other
suspect areas looking for the exceptionally high readings which would suggest
an area of potential moisture migration.
- Mapping – Assuming there is a problem area, perform a moisture
survey by taking methodical moisture readings throughout that area and
non-destructively mark the readings on the area’s surface. This can
be accomplished by various methods such as placing a piece of blue masking
tape on any area that has relatively higher moisture readings. Observe
the marked survey area and look for a trend that may lead to or indicate
the moisture migration source. This will be the spot to consider for intrusive
testing. Photograph the area for documentation purposes.
- Limitations of Moisture Meters
- Point-in-time reading. The moisture meter is only showing the relative
moisture reading at a given point in time (real time field readings) relative
to the various conditions (i.e. relative humidity; temperature) at the
point in time when the readings were taken. Actual readings may change
as the climatic conditions change or the moisture source content changes.
- Cannot measure non-conductive materials or metals. Avoid measuring near
metal corner beads and metal studs, which can affect the readings.
- Cannot measure vapor transmission. This measurement is not a substitute
for a quantitative measurement, such as the Calcium Chloride (CaCl) Dome
test.
- Substantiate how the Moisture Meter can be used to demonstrate degree of
relative moisture.
- Using certain types of moisture meters allows for non-destructive (non-intrusive)
testing and mapping (or moisture surveying) of a suspect area in order to
determine the area’s relative moisture condition. This is a relatively
quick process and gives the Inspector a tool to evaluate and identify probable
moisture sources and problem areas without intrusive testing. Using the
moisture meter will assist the Inspector to determine the various areas
of high moisture concentrations and determine the best areas to perform
intrusive testing for substantiating problems and their source of moisture.
The preceding article was researched and written by CTIOA Inc. Moisture
Meter Testing Committee.
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