What goes here
The pages in the rest of the site are meant to stay correct for years. This is where the shorter, more specific pieces go: a measurement, a correction, a claim tested against a number.
Most of them exist because a piece of advice is repeated everywhere without anyone checking it. Houseplants as natural dehumidifiers, bleach as a mold treatment on drywall, a bowl of salt in a damp room, leaving a window permanently cracked in winter. In every case there is a real mechanism underneath — the question is only whether it operates at a scale that matters in a house, and that is a question with a number attached.
Where the popular answer turns out to be right, that is said as plainly as when it is wrong. Cross-ventilation really does beat a cracked window. Calcium chloride really does work in a sealed closet. The point is not to be contrarian, it is to put a figure against the claim.
What the pieces have in common
Claims with a number attached
Pints per day, dollars per month, degrees of surface temperature. A remedy that removes an ounce a week is not a small version of a dehumidifier, it is a different category of thing, and only a number makes that visible.
Corrections to things everyone repeats
Several of the most common pieces of humidity advice have the physics backwards rather than merely exaggerated. Those are worth their own pages, with the mechanism explained rather than just contradicted.
Seasonal pieces
How low to set humidity in freezing weather, why basements turn humid in summer, why windows sweat in fall. The same house has opposite problems six months apart and the advice has to move with it.
Everything links back to a guide
Each post feeds one of the main branches rather than standing alone, so a short piece about one measurement always has the full treatment a click away.
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.
Seven humidity myths, measured
Most damp advice is repeated rather than checked. Here is each claim next to the quantity that settles it.
What a dehumidifier actually costs to run
Three numbers decide it, and one of them is a setting you control. Most people are paying for the 5% they did not need.
How fast does mold grow after water damage?
The clock everyone quotes is real, but it is a drying deadline rather than a growth deadline — and the distinction changes what you should do first.
Why your windows sweat and your neighbor’s do not
Same street, same weather, same thermostat — and one house wipes the glass every morning. Four variables explain it.
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.
Common questions
How often is anything here updated?
Pages carry the date they were last reviewed in the bar under the title. Guidance that rests on published standards — the DOE test method, EPA and ASHRAE recommendations — is checked against the current version when a page is revised rather than left to age quietly.
Do you test any of this yourselves?
Where a claim can be settled with a hygrometer and patience, the figures quoted are the ones that measurement gives. Where it rests on published work — germination thresholds, health associations, appliance test methods — the source is cited on the page rather than paraphrased into a bare assertion.
Are there affiliate links in these articles?
No. Nothing on this site earns a commission on a product, which is why the pages are free to say that a category of product is a waste of money and why the cheapest fix is at the top of every plan rather than the most profitable one.