Notes on indoor humidity
Measurements, corrections and the occasional debunking. Where the popular answer is wrong, we say so and show the numbers.
Latest
Do houseplants reduce humidity? No — they raise it
Peace lilies appear on every natural-dehumidifier list. Plants transpire — they move water from soil into your air.
Why modern dehumidifiers are rated for fewer pints
The machines did not get weaker. In 2019 the test moved from 80 °F to 65 °F, and the labels got honest.
When opening a window makes your humidity worse
Outdoor air at 80% can be drier than your indoor air at 60%. It can also be much wetter. The percentage alone cannot tell you which.
Why bleach fails on mold — and what works instead
On tile it works. On drywall and wood the chlorine stays on the surface while the water content soaks in and feeds what is underneath.
How low to set your humidity when it is freezing outside
The right indoor humidity in winter is not one number — it falls as the outdoor temperature does, and your windows tell you when you have overshot.
Why your basement is humid in summer and fine in winter
The one space in a house where winter is the dry season and opening a window in August is the worst thing you can do.
Categories
Condensation & Damp
Why water forms on surfaces, how to read what it is telling you, and the four causes of a damp wall.
Mold & Health
Where mold grows and why, what removes it, and how seriously to take it.
Equipment & Ventilation
Dehumidifiers, fans, ventilation systems — sizing, running costs and what the ratings mean.
Dry Air & Winter
The other half of the problem: heated houses, static shocks and how far to raise humidity.
Room by Room
The same problem behaves differently in a basement, a bathroom and a garage.
Myths & Tests
Folk remedies measured against what they actually remove. Where the popular answer is wrong, we say so.