Same physics, different room, different answer
A basement needs a lower target than a bedroom. A garage needs different equipment entirely. A bathroom is supposed to spike. Here is what each space actually needs.
| Room | Target | The reason it differs |
|---|---|---|
| Basement | 50% or below | Lower than the rest of the house, because the surfaces are colder |
| Bathroom | Under 60% within 20 min | Peak matters less than recovery time |
| Bedroom | 40–50% | Same as living space, but read it in the morning, not the evening |
| Crawl space | 55% or below | Achievable only once the ground is sealed |
| Kitchen | Under 60% | During and shortly after cooking |
| Attic | Tracks outdoor air | A healthy vented attic is close to outdoor conditions |
| Garage | 50–60% | Below 60% to protect steel from rust |
| Closet | 45–55% | Same as the room, which is the problem — it is usually higher |
Every room
Basement
The coldest surfaces in the house, and the one space where ventilating in summer makes things worse.
Bathroom
The only room where a huge humidity spike is normal. The number that matters is how long it takes to fall.
Bedroom
A closed room with people breathing in it all night. The mold turns up behind the furniture, where nobody looks.
Crawl space
The highest-value moisture repair in most US homes, and the one where old building practice was flatly wrong.
Kitchen
Only the bathroom produces more moisture. The difference is that most kitchens have a range hood that removes nothing.
Attic
Rarely its own problem. Attic moisture is usually the house below it, arriving somewhere nobody looks.
Garage
The space where the usual equipment fails — too cold for a compressor dehumidifier, and rust is the damage rather than mold.
Closet
The one space on this site where a DampRid tub is genuinely the right tool.