<60%
EPA recommends keeping indoor relative humidity below 60%, ideally between 30% and 50%, to limit mold.
U.S. EPA, A Brief Guide to Mold, Moisture and Your Home
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Indoor climate · Mold and humidity
Mold and humidity levels: find the real cause
Mold and humidity problems start a blame game fast. Was it the tenant's habits or the building? I analyze temperature and humidity data from simple loggers, calculate the dew point at cold walls, and tell you what the data shows.
Mold has a cause, and humidity data shows it
Mold needs moisture, and homes produce plenty of it. Showers, cooking, drying laundry, and breathing all add humidity. The risk peaks where warm, humid air meets a cold surface. Think exterior corners, closets on outside walls, and thermal bridges. The air cools at the wall, and relative humidity there climbs.
Property managers, landlords, and tenants all want the same answer. Is it how the unit is used, the building, or both? A single reading during an inspection can't tell you. A few weeks of logger data can. It shows real humidity levels, how often the unit gets aired out, and how cold the wall gets.
80%
Surface relative humidity, as a 30-day average, that ASHRAE uses as its mold-risk limit for building surfaces.
ASHRAE Standard 160
49°F
Dew point of room air at 68°F and 50% relative humidity. Surfaces colder than that get wet.
Standard psychrometric calculation (Magnus formula)
How I find the cause in your data
Plan the measurement
I tell you where the loggers go. One goes in the affected room, ideally near the cold wall. Another goes in a normal room for comparison. I also tell you how long they should run.
Analyze dew point and humidity
From temperature and humidity, I calculate how damp it gets right at the wall. I count how often it crosses the 80% line and see when heating and airing out happen.
Get a neutral report
Within 1–2 weeks you get a factual report with recommendations on ventilation and heating. If a building defect looks likely, I say so and recommend an on-site inspection.
Thought about it but never got around to it? Getting started takes two minutes.
- 01
Tell me what's going on
Use the inquiry form to tell me which room it is and what bothers you. It takes two minutes.
- 02
Send data or start measuring
If you already have a monitor, send me the export through a secure upload link. If not, I'll tell you which device is enough and where to put it.
- 03
Get your answer
Within one to two weeks, you get a short report: what's going on, why, and what to do first. No site visit needed.
Questions
Is this a legal expert report?
No. I'm not a certified mold inspector, and this is a data analysis. It gives landlords, tenants, and inspectors a neutral basis for the next step.
Do I need expensive equipment?
No. Simple temperature and humidity loggers are often enough. I help you pick them and place them.
How long should we measure?
Ideally 2–4 weeks during heating season. That's when cold walls cause the most trouble. Summer data tells you much less.
What does it cost?
It depends on the number of rooms and loggers. You get a clear quote before I start.