The 24 to 48 hour rule
EPA says water damaged areas should be dried within 24 to 48 hours to prevent mold. That does not mean the job is finished in two days. It means drying has to be well under way, with the water out and the gear running, inside that window.
Why the desert does not dry it for you
The North Las Vegas station averages about 4.27 inches of rain a year. The air outside is dry. Inside a closed wall cavity, under carpet pad or in the bottom plate of a wall, there is no air moving at all. Those spaces stay wet for a long time. That is where mold starts while the paint looks fine.
What decides the time
| Factor | Faster | Slower |
|---|---|---|
| Water type | Clean supply water | Category 3, more removal first |
| Class | Class 1, part of a room | Class 4, hardwood, plaster, concrete |
| Start time | Same day | Days later |
| Gear | Sized to the room | A box fan and an open window |
| Materials | Drywall and tile | Hardwood, cabinets, stone |
How gear is sized
Industry guidance puts air movers at about one per 10 to 16 linear feet of wet wall, plus one for each closet or small bath. A 12 by 12 foot room may need four or five. Dehumidifiers for a Class 2 loss are sized by taking the room's cubic feet and dividing by 50 to get pints per day. A 30 by 50 foot space with 8 foot ceilings needs about 240 pints a day.
A home dehumidifier is usually rated in the tens of pints. That is why one plugged into a soaked room does not keep up.
The finish line is a number
A moisture meter reading means little on its own. On the reference scale, a 12 does not mean 12 percent water. It means wetter or drier than a known dry spot. So the first visit takes a reading from a room the water never reached. That is the dry standard. Wet areas are dried until they match it, with three matching readings in a row. On the gypsum scale, drywall can be damaged at just over 1 percent moisture content.
Can you live in the house while it dries
Often yes with clean water. The gear is loud and warm and runs all the time. Sewage, mold and jobs with lots of open walls can change that. Ask on the first visit, and do not turn the equipment off at night. That undoes a day of drying.