How to Interpret UNI-T UT377C Moisture Readings, Colour Bars and Alarms Malaysia
The UNI-T UT377C Pinless Moisture Meter displays a numerical reading together with a colour indication and audible alarm.
These features help users recognise changing moisture conditions while scanning wood, drywall and masonry. However, the result must be interpreted according to the selected material mode.
A high number does not carry the same meaning in every mode.
Four Available Measurement Modes
The UT377C provides:
Softwood
Hardwood
Drywall
Masonry
Softwood and Hardwood modes display an estimated wood moisture percentage.
Drywall and Masonry modes display a relative value used to compare different areas of similar material.
Always confirm the selected mode before recording the result.
Understanding Wood Readings
In Softwood and Hardwood modes, the UT377C provides:
Measurement range: 4%–32%
Resolution: 0.1%
Specified value error: ±4%
A higher percentage indicates a higher estimated moisture condition within the instrument’s measurement capability.
The result can be affected by wood species, density, coatings, thickness and temperature. Measure several points and boards before making a decision about an entire batch.
Understanding Drywall and Masonry Readings
In Drywall and Masonry modes, the meter displays values from:
0 to 99.9
Resolution: 0.1
These are relative readings—not absolute moisture percentages.
For example, a masonry reading of 65 should not be reported as “65% moisture.” It should be compared with readings from a similar section believed to be dry.
A more accurate record would be:
Dry reference area: 18
Suspected damp area: 65
Test mode: Masonry
Observation: The suspected area produced a substantially higher relative reading.
What Does the Colour Bar Mean?
The UT377C uses a three-colour simulation bar:
Green
Yellow
Red
The colours provide a quick visual indication of changing moisture conditions.
Green generally represents a lower reading, yellow indicates an intermediate condition, and red indicates a higher reading based on the selected mode.
The colour bar is a screening aid. It does not replace correct material selection or comparison with a reference area.
When Does the Audible Alarm Activate?
The UT377C provides an audible warning when readings exceed its programmed thresholds.
According to the operating information:
In wood mode, the alarm activates when the reading is above approximately 24%
In building-material mode, the alarm activates when the relative reading is above approximately 60
The alarm is intended to attract the user’s attention. It does not automatically confirm severe water damage or an active leak.
What Should You Do When the Alarm Sounds?
When the meter produces an alarm:
Confirm the correct mode is selected.
Keep the sensor flat against the surface.
Repeat the measurement.
Scan the surrounding area.
Compare the result with a dry reference location.
Check for pipes, wiring or hidden metal.
Look for visible signs of moisture.
Record the location and reading.
If several nearby points produce high readings, the area may require further investigation.
Why Can a Dry Area Show a High Reading?
A high reading can also be caused by:
Metal pipes
Electrical wiring
Metal wall studs
Reinforcement bars
Screws and nails
Dense construction materials
Adhesive layers
Foil-backed insulation
Surface condensation
Material behind a thin panel
Scan around the point from several directions.
An isolated narrow pattern may indicate hidden metal, while a broader pattern may be more consistent with moisture spreading through the material.
Why Do Readings Change Between Materials?
Different materials have different densities and electrical properties.
Do not directly compare:
Drywall with concrete
Hardwood with softwood
Plaster with brick
Solid timber with engineered panels
Painted walls with tiled surfaces
For reliable comparison, use the same mode, similar material and consistent measuring technique.
Create a Simple Inspection Record
A useful moisture inspection record should include:
Date and time
Inspection location
Selected measurement mode
Reference-area reading
Suspected-area reading
Colour indication
Audible-alarm status
Visible symptoms
Photo of the test area
Follow-up reading after repair
This is more useful than recording only a single number without context.
Monitor Changes Over Time
After repairing a leak or drying the area, repeat measurements at the same marked locations.
Use:
The same UT377C mode
The same measuring position
Similar environmental conditions
The same sensor orientation
The same reference area
A downward trend can help indicate that the material is drying.
If the readings remain high or continue increasing, additional investigation may be necessary.
Correct Interpretation Is More Important Than One Number
The UT377C should be used as a comparison and screening instrument.
Reliable interpretation depends on:
Choosing the correct mode
Establishing a dry reference
Measuring several locations
Looking for consistent patterns
Considering hidden construction materials
Monitoring changes after repair
The numerical reading, colour bar and audible alarm should be evaluated together with visual inspection and knowledge of the tested material.
Contact MTM Precision for the UNI-T UT377C or assistance selecting a moisture meter for wood, building inspection and maintenance applications in Malaysia.
MTM Precision Sdn Bhd
Showroom & Service Centre: No. 29-1 & 29-2, Jalan Bandar 18, Pusat Bandar Puchong, 47160 Puchong, Selangor, Malaysia
Tel: 03-8080 7172
WhatsApp: +6016-660 7346
Email: mtmpre@yahoo.com
Website: www.mtmpre.com.my
30 Sep 2026
