Dry to the touch is not dry
Drywall, wood framing and concrete can feel dry on the surface while holding significant moisture inside. Close the walls or reinstall flooring too soon and that moisture stays trapped, which can lead to odor, swelling, peeling paint and microbial growth. That is why professional drying relies on instruments rather than touch.
The core idea is simple. Before or during the job, the contractor measures the same kinds of materials in an area of the building that did not get wet. Those reference readings become the drying goal. Wet materials are measured on a schedule, usually daily, and drying continues until they come within an acceptable range of the reference.
The vocabulary on a drying log
- Pin meter
- A moisture meter with two pins pushed into the material. Gives a reading at the pin depth and leaves small holes.
- Pinless meter
- Reads moisture through the surface without holes, by scanning. Good for mapping how far water spread.
- Reference or dry standard
- A reading taken on the same material in an unaffected area, used as the target.
- Relative humidity
- How much moisture the air holds compared with its maximum at that temperature.
- GPP (grains per pound)
- The actual amount of water vapor in the air. Lower GPP inside the work area than outside it shows dehumidifiers are working.
- Moisture map
- A sketch of the space showing where readings were taken and which areas were wet.
What a simple daily log might show
| Reading point | Reference (dry area) | Day 1 | Day 2 | Day 3 |
|---|---|---|---|---|
| Drywall, north wall, low | Dry baseline | Very wet | Wet | Near baseline |
| Bottom plate, north wall | Dry baseline | Very wet | Wet | Wet |
| Subfloor near source | Dry baseline | Wet | Near baseline | At baseline |
| Air in work area (GPP) | Outdoor GPP noted | High | Lower | Low |
How to follow the readings yourself
- Ask for the reference readings.Know which unaffected spot was used and what it read on day one.
- Get the moisture map.Ask for a sketch or photos showing where each reading point is, so the same spots are measured every day.
- Review the log as it is updated.A daily copy, by photo or email, lets you see whether readings are moving toward the goal.
- Question a stall.If one point is not improving after several days, ask whether a hidden layer, such as a second sheet of drywall or vinyl wallpaper, is trapping moisture.
- Confirm the final readings.Before equipment leaves, ask to see every point at or near the reference value.
General information for Aurora, not a quote or professional advice. In an emergency, call 911.