How to Use a Moisture Meter After Water Damage

Updated October 20, 2026. After a leak, use a moisture meter on the scale that matches the material, and read a dry spot of that same material before you read the wet spot. A pin meter reports percent moisture content in wood and drywall. A pinless meter scans a finished surface or a bare concrete slab without leaving holes. Write the scale next to every number. A 15 on a wood percent scale, a 15 on a 0–100 reference scale, and a 15 on a 0–300 scan are three different results.

How to Use a Pin Moisture Meter

A pin meter pushes two metal pins into the material and reads moisture at that depth. Delmhorst's TechCheck Plus manual tells the user to drive the pins to full penetration when the material allows it. On that meter the built-in pins reach about 5/16 inch (8 mm). Insulated pins read at the tip, so they can be driven deeper into a stud or through the face of drywall. As of October 20, 2026.

1. Set the material scale before the first hole. Use the wood scale on framing and subfloor. Use the drywall or gypsum scale on gypsum board. On a wood scale, a drywall reading is only a relative number. The TechCheck manual says pin mode on materials other than wood gives relative readings, and the user should compare a dry area with the wet area.
2. Read an unaffected piece of the same material in the same house. Write that number down with the scale name. That reading is the dry standard for this job.
3. Start where the water sat. On walls, that is usually the bottom of the drywall and the studs behind it. On a subfloor, read the top and, where you can reach it, the underside. Push the pins in parallel to the wood grain.
4. Record the percent and the scale together. Compare the wet spot with the dry standard, then with the meter-maker zones in the table below.
5. Move out in a grid until the readings match the dry area. One high spot is a wet spot. A whole wall of high spots is a wet assembly.
6. Keep the pins out of finishes where a wire or pipe may sit behind the surface.

How to Use a Pinless Moisture Meter

A pinless meter sits flat on the surface and reads a layer under the sensor. It leaves no holes, and it does not see the far side of a wall cavity. The ceiling check in the photo on this page is that kind of scan: the sensor is flat on the texture, above a stain at the wall joint.

1. Select the material mode if the meter has one. If the only scale is a relative number, label the reading "relative" in your notes.
2. Learn the depth before you trust the number. The Tramex Concrete Moisture Encounter CME5 user guide says the concrete reading reaches about 3/4 inch (20 mm) into a clean, bare slab. A wall scan is shallower than a deep pin electrode. As of October 20, 2026.
3. Scan a known dry area of the same material first. That baseline is what "higher" means on this meter, in this house.
4. Scan the suspect area slowly. Include the bottom of walls, the subfloor near the wet wall, and ceiling-to-wall joints.
5. Treat a high scan as a reason to look closer. On wood or drywall, confirm it with a pin reading where a small hole is acceptable. A pinless drywall scan on the TechCheck is a 0–300 relative scale. Delmhorst says to compare it with a dry area. It does not convert that scan into the drywall percents in the table.
6. On concrete, read the concrete percent scale on clean, bare concrete. The CME5 guide says readings through paint, coatings, or adhesive are comparative. During a dry-out, watch the number fall toward an unaffected area of the same slab.

Pin, pinless, combination, hygrometer, and thermal tools answer different questions. The comparison of those five is on 5 types of moisture meters for water damage.

The Best Moisture Meter for a Water-Damage Check

The best moisture meter is the one whose scale matches the material in front of you. A pin meter with a drywall scale and a wood scale is the right tool for a percent reading in gypsum and in framing. A pinless concrete meter is the right tool for a slab you should not drill. A single "best" model does not cover both jobs. Meters that add a hygrometer or a thermal camera are covered with the other types on the page linked above.

Store meters are useful on a small, clean spill you caught the same day. A supply-line break, a slab leak, or water that sat overnight needs the same readings written down over several days. That record is a drying log. When the wet column in the table stays high after the surface looks dry, the next step is a documented dry-out through water damage restoration.

Typical Readings After Water Damage

These bands are the meter-maker zones for the scale named above each table. They are a place to start. They are a poor substitute for a dry standard taken in the same house, on the same material, with the same meter. The BDX-20 and BDX-30 manual (May 2024) says specific jobs may need different thresholds than the default lights. As of October 20, 2026.

Drywall: pin meter, drywall % scale

Wood framing or subfloor: pin meter, wood % scale

Bare concrete slab: pinless meter, 0–6 % scale

Drywall. Two Delmhorst pin manuals agree on this split. The TechCheck Plus manual calls 0.1% to 0.5% sufficiently dry, 0.5% to 1% borderline, and anything above 1% too wet for paint or wallpaper. It also says a reading above 1% is enough moisture for mold only when high relative humidity and a food source are present too. The BD-2100 manual uses the same gypsum lights: green through 0.5%, yellow from 0.5% to 1%, red above 1%. The May 2024 BDX manual is a tenth tighter: green 0.1% to 0.4%, yellow 0.5% to 0.9%, red at 1% and above. As of October 20, 2026.

Wood framing and subfloor. The May 2024 BDX manual sets the wood lights at green 6% to 15.9%, yellow 16.0% to 18.9%, and red at 19% and above. Wagner Meters says lumber used for framing usually ranges from 12% to 19%, and that anything above 19% is susceptible to mold and decay. A second Wagner page says decay fungi generally grow in wood only when moisture content is greater than 20%. A 17% stud can sit inside both Wagner's usual framing range and Delmhorst's yellow light. Compare it with an unaffected stud before you call it water damage. Wagner also says that, when hardwood flooring goes down, the finished floor's moisture content needs to be within 2 to 4 percentage points of the wood subfloor, depending on the board width. As of October 20, 2026.

Concrete. Tramex says a new slab can be dry enough for a floor covering at 3.5% to 4.5% moisture content, with 4.5% the figure for normal conditions, 4.0% often preferred in drier air, and 3.5% in very dry air. The CME5 scale that carries those percents runs from 0% to 6% and applies to clean, bare concrete. A resilient-flooring installation sheet that specifies the Tramex Concrete Moisture Encounter says readings should not exceed 4.5 on the upper scale. Tramex's restoration testing note separates that new-slab covering test from a water-loss dry-out: the restoration goal is to bring the slab back to pre-loss conditions, and the useful signal during drying is whether readings are falling. As of October 20, 2026.

The reading still depends on the meter and the scale. Delmhorst's reference scale on the BDX is 0 to 100, and its default "wet" light does not turn on until 95. That light is a different tool from the wood and drywall percents above. Pinless drywall scans on the TechCheck run 0 to 300. Restoration & Remediation Magazine, quoting the current IICRC S500, describes the dry standard as a reasonable approximation of the moisture content a material had before the water arrived, taken on similar material in an unaffected area, and the drying goal as the target the restorer sets at the end of drying. The same article says an acceptable dry standard is within 10% of the pre-loss level of similar materials, and that material should not be left at a level that supports microbial growth. Encircle's S500 notes describe the same 2021 practice: a drying goal within 10% of the dry standard, taken with the meter you are actually using. IICRC publishes S500 as the Standard for Professional Water Damage Restoration; the percent table on this page is the meter-maker zones, and the dry standard is the job-specific target. As of October 20, 2026.

Indoor wood also moves with the room. Wagner says the ideal moisture content for a piece of wood is usually 6% to 12%, and that the equilibrium moisture content is the number the wood will actually settle to in a given place. The USDA Forest Products Laboratory review of wood-frame buildings (FPL-GTR-174) puts equilibrium moisture content at 70°F between about 4.5% and 16% as relative humidity runs from 20% to 80%. A humid house can hold a higher normal wood reading than a dry house. As of October 20, 2026.

What Is a Moisture Meter?

A moisture meter is a handheld instrument that reports how much water is in a solid material. Restoration crews use one to find the edge of a leak, to decide whether drywall and framing can stay, and to show that those materials have returned to a dry standard. Homeowners use the same idea on a smaller spill: check the material, compare it with a dry spot, and keep checking until the two spots agree.

The meter does not measure whether a room feels dry. Air humidity is a hygrometer reading. A wall can scan wet in a room that feels normal, and a room can feel muggy while the studs are already at the dry standard.

What a Moisture Meter Measures

It measures water in the material under the sensor or between the pins. On a water-damage job the usual materials are drywall, wood framing, wood subfloor, and concrete. Some meters also have scales for other finishes. Carpet and fabric can be checked with a reference scale, and that result is a comparison with a dry patch of the same carpet, which is a different kind of number from the percents in the table.

How the Meter Turns Moisture into a Number

A pin meter is a conductance meter. Delmhorst's May 2024 BDX manual calls the BDX-20 and BDX-30 pin-type conductance meters, and it says other factors can affect the accuracy of those readings. Species and material corrections change how the meter displays the result. The USDA Forest Products Laboratory paper Electric Moisture Meters for Wood says the same class of meter is a conductance meter, also called a resistance meter, and that conductance increases as moisture content increases. Conductance is the reciprocal of resistance, so the resistance between the pins falls as the wood gets wetter and the moisture number on the display goes up. The display is only as meaningful as the scale you selected. As of October 20, 2026.

A pinless meter uses an electromagnetic field. The CME5 guide describes a low-frequency signal sent from electrodes in the base of the meter. The strength of that signal changes with the moisture in the slab, and the meter turns it into a concrete percent on bare concrete or a comparative number through a coating. Metal, foil-backed insulation, and water sitting on the surface can push a scan around. When a scan and a pin reading disagree, trust the reading whose scale matches the material, and take the other one as a map of where to test next.

When a Moisture Meter Helps

Use one whenever water may still be in a material after the surface looks dry. That includes the day of a leak, the days the drying equipment is running, and the day before new flooring goes on a subfloor. A single visit shows where the water is. Repeat visits show whether it is leaving.

The practical gains are straightforward:

• A number you can compare with a dry area of the same material
• An edge to the wet area, so drying effort goes where the water is
• A record for the drying log and for the insurance file
• A check before paint, wallpaper, or new flooring goes back on

A meter does not dry the building, and it does not identify mold. It tells you whether the material is still holding water. If the readings stay in the wet column, or the wet area is bigger than one room, water damage restoration is the work that maps, dries, and documents the loss.