A moisture meter tells you where a material is wetter than it should be. Pinless meters such as the Tramex ME5 scan walls, floors and timber without damage, soil meters such as the Reotemp read a probe tip pushed into compost or soil, and a laboratory moisture analyzer gives true percent water by weight. Pick the instrument from the material and the decision you must make, then check how the reading is expressed, because most field meters report a relative scale, not a percentage.
In this guide
- Which type of moisture meter do you need?
- Does a moisture meter read a percentage?
- How does a pinless meter work on walls, floors and timber?
- How does a soil moisture meter work?
- Can a moisture meter approve a concrete slab?
- Which moisture meters does ERE list?
- How do you choose and use one, step by step?
- Frequently Asked Questions
Which Type of Moisture Meter Do You Need?
The material decides. Pin meters push two electrodes into the material and read electrical resistance, which suits timber and lumber at depth. Pinless (non-destructive) meters read through the surface with a sensor in the base, which suits finished walls and floors you cannot drill. Soil probes read at a tip. A laboratory analyzer dries a weighed sample and reports the water lost. The table maps each to the question it answers.
| Question | Instrument | What the reading means |
|---|---|---|
| Where is the wet area behind this wall or under this floor? | Pinless meter (Tramex ME5) | Relative 0 to 100 reference scale on drywall, plaster, tile and masonry; %MC on wood |
| Is this soil or compost pile wetter than the next one? | Soil probe (Reotemp) | Relative 0 to 10 wetness scale at the probe tip |
| What is the exact water content of this sample, by weight? | Laboratory moisture analyzer (OHAUS MB series) | Percent water, from loss on drying |
| Is this concrete slab dry enough for flooring? | In situ relative humidity probes (ASTM F2170) | Percent relative humidity inside the slab |
Does a Moisture Meter Read a Percentage?
Usually not. Outside of wood, a field moisture meter reports a relative number that you compare against a dry reference reading from the same material. The Tramex ME5 record states a wood moisture content scale of 5 to 30% and a separate reference scale for building materials of 0 to 100. Its dial shows both, and the 0 to 100 scale is marked comparative. The Reotemp record describes a relative moisture content derived from a probe you calibrate yourself.
The practical rule: take a reading on material you know is dry, then map outward until the needle climbs. The change is the signal. The absolute number is not a pass or fail on its own, and two different materials with the same needle position are not equally wet. If you need a true percentage by weight, that is a job for a laboratory moisture analyzer.
How Does a Pinless Meter Work on Walls, Floors and Timber?
It sends a low-frequency signal into the material through electrodes in the base of the instrument and reads the electrical impedance, then converts the strength of the current into a value shown on the dial. That is the method described in the product record for the Tramex ME5 Moisture Encounter Meter. It leaves no holes, so you can survey a finished room.
Two features matter in the field. First, five sensitivity ranges: wood and timber, shallow depth, drywall and roofing, plaster and tile, and masonry. Choosing the wrong range is the most common reason two inspectors get different results on the same wall. Second, dual-depth penetration: a shallow signal reaches up to 10 mm and a deep signal up to 30 mm, so you can compare the surface with the core and limit the influence of the substrate under a covering.
The record lists these uses: locating moisture problems within and behind building materials in the building envelope, mapping the extent of moisture damage, and monitoring progressive drying. For a drying job, log the same grid of points each visit. A falling trend at the same points is your evidence that the material is drying, and a flat or rising one tells you the source is still active.
Why speed matters: Health Canada notes that mould will begin to grow in an area with excessive moisture within 48 hours, and that mould reappears unless the cause of the moisture problem is identified and solved (Health Canada, Guide to addressing moisture and mould indoors). A meter helps with the second half: it finds the wet material that a visual inspection misses. If your question is whether mould is already present, see our bioaerosol sampler guide.
How Does a Soil Moisture Meter Work?
The Reotemp Soil Moisture Meter gives the moisture content of a compost pile or soil sample through a sensor at the bottom of the probe. Per the record, the probe is sensitive only at the tip, so the reading is the moisture at the depth where the tip sits. You calibrate it by inserting the tip into a saturated sample of compost or soil and setting the needle to 10, then insert it at the depth you want to measure and read a relative moisture value straight away.
The record adds that the meter is sensitive to changing salt content, so it can track leachate as well as moisture. Treat that as a caution too: a salty or amended sample reads differently from the one you calibrated on, so calibrate in a sample that resembles the one you are measuring.
Stem length sets your depth. The record lists 24, 36, 48 and 60 inch stems (REO-MM24, REO-MM36, REO-MM48, REO-MM60), which is about 61, 91, 122 and 152 cm. That is our unit conversion, not a manufacturer figure. The stem is 5/16 inch in diameter, the unit runs on one AAA battery, and the spec lists a rugged metal construction. For site-wide soil work, pair it with the tools in our soil sampling equipment guide.
Can a Moisture Meter Approve a Concrete Slab?
Not on its own. A surface or pinless meter is a screening tool: it shows where a slab is relatively wetter. The acceptance test most flooring manufacturers ask for is different. ASTM F2170 covers the determination of percent relative humidity in concrete slabs using in situ probes, and its significance section notes that excess moisture in a slab after floor covering is installed can cause debonding and microbial growth, that manufacturers generally require moisture testing before installation, and that results describe the slab only at the time and in the locations tested (ASTM F2170, Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes).
What this means for a buyer: use the pinless meter to choose where to place probes and to monitor drying between formal tests, and follow the flooring manufacturer's written requirement for the acceptance test. ERE does not currently list in situ relative humidity probe kits. Ask us if your specification calls for one.
Which Moisture Meters Does ERE List?
Tramex ME5 Moisture Encounter Meter
Non-destructive and dual-depth, with five sensitivity ranges and an analog dial. Wood moisture content 5 to 30%, a 0 to 100 reference scale for building materials, 10 mm and 30 mm penetration, ABS body, two AA batteries, 160 x 85 x 38 mm and 270 g per the record. The record lists a datasheet and user manual. See the Tramex ME5 page.
Reotemp Soil Moisture Meter
Tip-sensitive probe on a 0 to 10 relative wetness scale, in four stem lengths from 24 to 60 inches, for compost piles, farms and nurseries per the record. See the Reotemp Soil Moisture Meter page.
Laboratory moisture analyzers
For percent water by weight, ERE lists the OHAUS MB series, for example the OHAUS MB23. Our moisture analyzer buyer's guide compares the models.
Pin-type meters
ERE does not currently list an active pin-type moisture meter. If your work is lumber, firewood or timber at depth, tell us the species and range and we will confirm what we can supply. Browse the full moisture meters collection.
How Do You Choose and Use a Moisture Meter, Step by Step?
- Name the material. Wood, drywall, plaster, masonry, soil and compost each point to a different range or instrument.
- Decide what the number must do. Locate and map wet areas, track drying over time, or prove a threshold. Only the last needs a formal test method.
- Choose pinless, probe or analyzer. Finished surfaces need pinless, soil needs a probe, a true percentage needs an analyzer.
- Take a dry reference. Read a material you know is dry and note the needle position before you survey.
- Select the right range and depth. On the ME5, set the material range and compare the shallow and deep signals.
- Log a fixed grid. Record the same points on every visit so a trend, not a single number, drives the decision.
Need help choosing a moisture meter?
ERE Inc. has been Canada's environmental equipment specialist for 30+ years. Tell us the material, the survey and the specification, and we will match the instrument.
→ Request a Quote | 1-888-287-EREC | Browse Moisture Meters | sales@ereinc.com
Frequently Asked Questions
What is the difference between a pin and a pinless moisture meter?
A pin meter pushes two electrodes into the material and reads electrical resistance, so it leaves small holes. A pinless meter reads through the surface with a sensor in its base and leaves no marks, which suits finished walls and floors.
How deep does the Tramex ME5 read?
The product record gives up to 10 mm for the shallow signal and up to 30 mm for the deep signal. Comparing the two helps separate surface moisture from moisture in the core.
Is a moisture meter reading a percentage?
Only on wood, where the ME5 dial reads 5 to 30% moisture content. For drywall, plaster, tile and masonry it reads a comparative 0 to 100 scale, and the Reotemp soil meter reads a relative 0 to 10 scale.
Can I use a moisture meter to test a concrete slab before flooring?
A meter can screen a slab, but ASTM F2170 specifies in situ relative humidity probes for the determination, and flooring manufacturers generally require moisture testing before installation. Follow the manufacturer's written requirement.
How do I calibrate the Reotemp soil moisture meter?
Insert the tip into a saturated sample of compost or soil and set the needle on the scale to 10. Then insert the probe at the depth you want to measure to read a relative moisture value.
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- Soil Sampling Equipment in Canada: Augers, Core Samplers and Split Spoons
- Indoor Air Quality Monitoring for Commercial Buildings
- Choosing a Bioaerosol Sampler in Canada
Lire en français : Humidimètre : guide de choix sans broches, à broches et pour sol au Canada