Dry to the touch isn't dry
Drywall, wood framing and concrete can feel dry on the surface and still hold a lot of moisture inside. Close the walls or put the flooring back too soon and that moisture stays trapped, which leads to odor, swelling, peeling paint and microbial growth. That's why professionals dry by instrument, not by touch.
The method is simple. Before or during the job, the contractor measures the same kinds of materials in a part of the building that stayed dry. Those reference readings become the drying goal. The wet materials get measured on a schedule, usually daily, and drying continues until they land within an acceptable range of the reference.
The words on a drying log
- Pin meter
- A moisture meter with two pins pushed into the material. It reads at the pin depth and leaves small holes.
- Pinless meter
- Reads moisture through the surface without making holes. Good for mapping how far the water spread.
- Reference or dry standard
- A reading on the same material in an unaffected area, used as the target.
- Relative humidity
- How much moisture the air holds compared with the most it can hold at that temperature.
- GPP (grains per pound)
- The actual amount of water vapor in the air. A lower GPP inside the work area than outside shows the 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 the source | Dry baseline | Wet | Near baseline | At baseline |
| Air in work area (GPP) | Outdoor GPP noted | High | Lower | Low |
Follow the readings yourself
Ask for the reference readings
Learn which unaffected spot they used and what it read on day one.
Get the moisture map
Ask for a sketch or photos of every reading point, so the same spots get measured each day.
Review the log as it updates
A daily copy, by photo or email, shows you whether readings are moving toward the goal.
Question a stall
If one point hasn't improved 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 the equipment leaves, ask to see every point at or near its reference value.
General information for Aurora, not a quote or professional advice. In an emergency, call 911.