Humidity & condensation guides
Start with the symptom you actually see. Each guide explains what to measure, gives you a page-specific quick check, and then links into the full Home Moisture Lab when comparing rooms or saving history adds value.
Choose the guide by the question you are trying to answer
| If you notice… | Measure first | Best starting point |
|---|---|---|
| Wet or fogged windows | Room temperature, RH, outdoor temperature | Window condensation check |
| Basement RH much higher than upstairs | Temperature + RH on both floors at the same time | Basement vs upstairs comparison |
| Bedroom RH jumps overnight | Before-sleep and morning temperature + RH | Overnight bedroom test |
| Bathroom stays humid after a shower | Baseline, 30-minute and 60-minute readings | Bathroom recovery test |
| RH numbers seem contradictory | Temperature + RH, then compare dew point | Dew-point quick check |
| You are not sure how to measure | Sensor position, time and room conditions | 2-minute measuring workflow |
The quick checks run in your browser and do not diagnose leaks, mold or hidden material moisture. They are designed to tell you what to measure next.
Window condensation
Compare room dew point with the coldest glass, frame or reveal — and test how outside temperature changes the margin.
Basement humidity
Separate “the basement is cooler” from “the basement actually contains more water vapor.”
Bedroom humidity overnight
Use evening and morning snapshots to see whether dew point rose or RH climbed mainly because the room cooled.
Bathroom drying
Measure the drying response after a shower instead of judging the peak humidity alone.
Dew point at home
Understand why dew point tracks vapor level differently from relative humidity and how it connects to surface temperature.
How to measure indoor humidity
Where to place a hygrometer, when to take readings and which common measurement mistakes can distort a condensation check.
When should you leave the guide and use the full Lab?
Use the page-specific quick checks for one question. Use the full Lab when you want to compare several rooms, enter a measured surface temperature, test a different indoor RH target, save repeated snapshots, export history or share a result.