How we made this guide: picks, prices and specs come from our catalog and the makers' published specs, owner quotes come from customer reviews on our product pages and the guide was drafted with AI help, then checked and edited by Trevor Hall.
Before you install flooring, test the slab the way the flooring or adhesive maker's installation instructions require, which is often in-situ relative humidity (RH) probes under ASTM F2170 and sometimes a calcium chloride test under ASTM F1869. A moisture meter for concrete, such as the Tramex CME5 at $645, is the fast first pass: it shows where the slab is wetter so you know where to put the probes. Plan on at least three days for an RH test: 48 hours with the building at service conditions, then at least 24 hours for the probes to settle in their holes. The meter survey itself takes minutes and needs no drilling.
The meter gives you a map, not the pass or fail number. ASTM's own guide for these meters, F2659, describes them as a preliminary, comparative check of the upper inch of the slab, not a basis for accepting a floor. The probe or calcium chloride result is what you compare with the flooring maker's limit.
The three tests and what each one does
| Test | What it measures | Where it sits in the job |
|---|---|---|
| Concrete moisture meter survey (ASTM F2659 guide) | Comparative moisture in the upper layer of the slab, non-destructive | First pass. Finds wet spots and picks probe locations |
| In-situ RH probes (ASTM F2170) | Relative humidity inside the slab, in drilled and lined holes | The quantitative test many flooring makers ask for |
| Calcium chloride (ASTM F1869) | Moisture vapor emission rate in pounds per 1,000 square feet per 24 hours | Used when the flooring maker asks for it |
Flooring makers' limits vary by product and by test, so the number that counts is the one printed in your flooring or adhesive instructions. This guide does not give a universal pass mark. For how to read a meter's scale on different materials, see our moisture meter readings chart.
What you need
A basic survey takes one concrete meter. A full RH test adds probes, hole liners and a way to drill the holes. Tramex makes the tools below, and we carry the line in our Tramex collection and in the wider moisture meter collection.
Which tool for which job
| Job | Tool | Price |
|---|---|---|
| Estimates and slab survey | Tramex CME5 | $645 |
| Survey with the option to add RH probes | Tramex CMEX5 | $975 |
| RH probes for a CMEX5 | AP-F2170-B accessory pack | $1,490 |
| Depth profile with a Tramex meter | Tramex CMP | $805 |
| Meter, one RH probe and wood probe in one case | Flooring Inspector Kit | $1,820 |
Survey meter
Tramex CME5 - Concrete Moisture Encounter CME5
$645 · 5.0 from 8 reviews
Analog, non-destructive meter for the first pass over the whole slab.
The CME5's analog concrete scale reads 0% to 6% MC (Tramex's figure), measures to about 3/4 in (20 mm) deep and runs on a 9V battery. It is an analog meter that works by electrical impedance, with Bluetooth for the Tramex Meters App. Tramex lists it as supporting ASTM F2659 surveys. The F2170 probe pack does not list it as compatible, so it cannot run the RH test. It does take the Tramex CMP depth probe covered below.
“It is a quick and accurate tool to have while doing estimates.”
Tramex CME5 owner · 5 out of 5 stars
Survey plus RH
Tramex CMEX5 - Concrete Moisture Encounter CMEX5
$975 · 5.0 from 3 reviews
Digital meter that also pairs with the Hygro-i2 probe pack for F2170 work.
The CMEX5 is the digital model, and it is one of the meters the F2170 accessory pack below lists as compatible. If one meter has to cover both the survey and the RH test, this is the one in this group to start from.
“Used on several jobs and it worked great.”
Tramex CMEX5 owner · 5 out of 5 stars
RH test pack
Tramex ASTM F2170 Accessory Pack - AP-F2170-B
$1,490 · 5.0 from 1 review
12 reusable Hygro-i2 probes, 100 liners and a salt check for F2170 testing.
The AP-F2170-B pack holds 12 Hygro-i2 reusable RH sensors, 100 hole liners (3/4 in, 19 mm) and a salt check to confirm the probes read correctly. Its spec rows list the CMEX5, MEX5 and DL-RHTX as compatible devices.
“I used it for several jobs. Very satisfied”
Tramex ASTM F2170 Accessory Pack owner · 5 out of 5 stars
Inspector kit
Tramex Flooring Inspector Kit - FIK
$1,820
CMEX5, one Hygro-i2 probe, wood pin probe and IR thermometer in one case.
The Flooring Inspector Kit bundles a CMEX5 with one Hygro-i2 RH probe, hole liners, a pin-type wood probe, an infrared surface thermometer, an extension handle and a hard case (Tramex's kit list). One probe is enough to learn the RH routine. F2170 calls for at least three tests in the first 1,000 square feet, though, so add probes such as the AP-F2170-B pack before you run a full test.
Step 1: Read the flooring maker's instructions first
Find out which test the flooring or adhesive maker requires, what number it accepts and how many tests it wants. Makers differ, and a slab that suits one product can fail another. Write the requirement on your job sheet before you touch the slab.
Step 2: Survey the whole slab with the meter
Press the meter flat on the clean, bare concrete and read the scale or display. Work in a grid across the whole floor, with extra readings near walls, doors, plumbing, columns and any area that looks darker or stained. Mark the high readings. These are the spots the meter says are wetter than the rest, and they decide where the probes go.
Treat the readings as comparisons within this slab. A single meter reading does not tell you whether the floor passes. ASTM F2659 also notes that meter readings tell you less on slabs 6 inches or thicker, slabs with no effective vapor retarder, lightweight aggregate concrete and slabs with curing compounds or sealers. On those floors, lean on the F2170 probes. Some owners like the speed: one reviewer on our CME5 page says there is no drilling or difficult prep and that they can take a number of readings in rapid time.
Step 3: Decide how many RH tests to run
Before any RH test, F2170 asks for the slab and the air above it to be at normal service temperature and humidity for at least 48 hours, and for those conditions to hold through the test. Get the building's heating or cooling running early and log the room conditions.
ASTM F2170 calls for three RH tests in the first 1,000 square feet and one more for each additional 1,000 square feet. Put at least one probe in the wettest area your survey found, and spread the rest across the floor. Your flooring maker may ask for more.
| Floor area | RH tests F2170 calls for (our calculation: 3 for the first 1,000 sq ft plus 1 for each additional 1,000) |
|---|---|
| 1,000 sq ft | 3 |
| 2,000 sq ft | 4 |
| 5,000 sq ft | 7 |
| 10,000 sq ft | 12 |
One AP-F2170-B pack (12 probes) covers a 10,000 square foot floor in one round.
Step 4: Drill the holes and set the liners
For a slab that dries from the top surface only, F2170 sets the hole depth at 40 percent of the slab thickness. A 6 inch slab means a hole about 2.4 inches deep (our calculation: 6 x 0.40). A slab that dries from both the top and the bottom uses 20 percent of the thickness instead, about 1.2 inches in a 6 inch slab (our calculation: 6 x 0.20). Ask the general contractor or engineer which case your slab is before you drill. Clean the dust from each hole, then seat the liner so the probe measures the air inside the slab and not the room.
Step 5: Let the probe equilibrate, then read
The sensor needs time to come to the humidity inside the hole. F2170 calls for at least 24 hours of equilibration before the reading is taken. Tramex has a short maker video on the 24-hour wait. Keep the room at those service conditions until you read, and record the RH and temperature for each hole.
Step 6: Calcium chloride, when the maker asks for it
ASTM F1869 measures the rate of moisture vapor leaving bare concrete, in pounds per 1,000 square feet over 24 hours. Its scope says it is not for gypsum concrete or lightweight aggregate floors and not for use over coatings, reactive penetrants or patching and leveling compounds. Follow the kit maker's and the standard's steps for dish placement and timing. If your flooring maker names only RH, you do not need this test.
Step 7: Record the results and compare
List every reading with its location, the date, the slab temperature and the room conditions. Compare each one with the limit in the flooring maker's instructions. If any reading is over the limit, stop and talk to the flooring maker or your inspector before installing. The Tramex Meters App can log survey readings by Bluetooth on meters that support it.
Optional: the in-situ moisture probe
The Tramex CMP, called the Determinator, connects to the CME5, CMEX5, CME4 or CMEX2 and reads moisture content at the surface and down to 4 inches. The probe is 3/4 in (19 mm) across and goes into a drilled hole, so it is not a non-destructive test. It uses the Tramex Unified Concrete Moisture Test Method, which is Tramex's own method and not an ASTM test, so it does not replace the F2170 or F1869 result a flooring maker asks for.
Depth profile
Tramex CMP - Concrete Moisture Probe
$805
Adds readings from the surface down to 4 in using Tramex's own method.
Common mistakes
- Treating a meter reading as the pass or fail number.
- Skipping the flooring maker's instructions and guessing at a limit.
- Running too few probes for the floor area.
- Reading the probe before the equilibration time is up.
- Testing over coatings, patching compounds or sealers, then trusting the number.
- Using a calcium chloride kit on a floor the standard excludes.
If you want to read how pin and pinless meters differ, see pin vs pinless moisture meters. If the floor is concrete you plan to polish rather than cover, our concrete buffing guide picks up from there.
Frequently asked questions
Do moisture meters work on concrete?
Yes, a concrete moisture meter works as a survey tool. It reads the upper inch of the slab without drilling and shows which areas are wetter. It does not replace an RH probe or calcium chloride test when your flooring maker requires one.
What is an acceptable moisture level in concrete?
It depends on the flooring or adhesive maker. Each one sets its own limit for the test it requires, and the limits vary between products. Use the figure in the installation instructions, not a general rule.
What is the best test for concrete moisture?
The best test is the one your flooring maker specifies. Many makers ask for in-situ RH probes under ASTM F2170, and some accept or ask for calcium chloride under ASTM F1869. A meter survey comes first to choose the test locations.
How can I check concrete moisture myself?
You can survey the slab with a concrete moisture meter, which takes minutes and needs no drilling. For a result you can compare with a flooring limit, run the RH or calcium chloride test the flooring maker names, following the standard's steps.
How can I find the most accurate moisture meter for concrete floors?
Start with what you need the number for. For surveys, the Tramex CME5 and CMEX5 both measure to about 3/4 in. For RH testing, choose a meter and probe set that lists ASTM F2170, such as the CMEX5 with the AP-F2170-B pack or the Flooring Inspector Kit.
How much does a concrete moisture meter cost?
In our range, Tramex's analog CME5 is $645 and the digital CMEX5 is $975. A full F2170 setup adds a probe pack such as the AP-F2170-B at $1,490.
Does moisture come up through a concrete floor?
It can. A slab with no effective vapor retarder under it can keep drawing moisture from below, which is one reason ASTM F2659 points to F2170 probes for those slabs rather than a meter alone.
Test the slab before you install
Related guides
- Moisture Meter Readings Chart: Normal Levels for Drywall, Wood and Concrete
- Pin vs Pinless Moisture Meters: Which One Should Restorers and Inspectors Buy?
- Best Moisture Meters for Water Damage, Drywall and Building Inspection
- How to Buff and Polish Concrete Floors With a Floor Machine (Not Grinding)
