Normal residential drying takes three to five days. Class 1 damage can finish in two; hardwood and plaster take longer. If day four looks like day one, something specific is wrong, and it is almost always one of five things.
1. Not enough dehumidification
This is the most common cause by a wide margin, and it is counterintuitive.
Air movers do not dry anything. They lift moisture out of materials and put it into the room air — deliberately. Something then has to take it out of the air, and that is the dehumidifier's job.
A room with six air movers and one undersized dehumidifier reaches equilibrium: the fans keep evaporating, the air keeps saturating, and the moisture goes back into the materials as fast as it leaves. The drying curve flattens and stays flat.
The check is the relative humidity in the room. If it is not being pulled down and held well below the outside air, the dehumidification is short.
2. The doors and windows are open
An understandable instinct, and usually wrong. Once dehumidifiers are running, the room is a closed system on purpose. Opening it to outdoor air on a humid day brings in more moisture than it removes.
Open windows help only when the outdoor air is genuinely drier than the indoor air — which in most of the United States, in summer, it is not.
3. Moisture is trapped behind something
Drying works on surfaces that air can reach. Where it cannot, the material stays wet indefinitely:
- Vinyl or laminate flooring over a wet subfloor — the covering is a vapour barrier holding water underneath.
- Wallpaper or gloss paint on wet drywall.
- Insulation in a wall cavity with no path for air.
- Under cabinets and kickboards, where the toe space traps water no fan reaches.
The fix is access: pulling base trim, drilling cavity vents, lifting a section of covering, removing kickboards. A drying plan that has stalled and does not include opening something up is not going to finish.
4. The materials are simply slow
Not everything dries in five days, and expecting it to leads to the wrong intervention.
Hardwood, plaster, concrete and dense engineered products hold bound water — moisture inside the material rather than sitting in pores. It comes out slowly no matter how much equipment is in the room. Hardwood commonly takes one to three weeks with a specialty mat system.
If the readings are moving, even slowly, the job is working. Flat readings are the problem, not slow ones.
5. Water is still arriving
Obvious, and it happens more than it should. A leak that was not fully fixed, an intermittent leak that only appears when an upstairs bathroom is used, groundwater coming through a foundation after rain.
The tell is readings that fall and then rise again, particularly on a schedule.
The only way to know: monitor, do not guess
A drying job should have daily readings — moisture content of affected materials against a dry reference elsewhere in the house, plus temperature and relative humidity in the room.
Ask for the moisture log. Any competent contractor keeps one because the insurer wants it, and it answers the question this page is about in ten seconds. Falling readings mean wait. Flat readings for two consecutive days mean something in the list above.
What "dry" actually means
Not "feels dry". The target is the moisture content of the affected material matching an unaffected reference of the same material in the same building — typically within a few percentage points.
Material that feels dry to the hand routinely holds enough moisture to grow mould behind the paint, and that is the version of this problem that reappears in November as a smell nobody can locate.