Inputs
Results
Who This Score Is For
- Homes screening humidity, odor, condensation, and water-damage signals before mold risk is ignored too long
- Users who need a structured triage path instead of relying on one RH reading alone
- Buyers deciding whether the issue is a moisture-control problem, a building-water problem, or a remediation problem
How This Score Works
- Scores increase when indicators suggest persistent moisture (condensation, leaks, stains) and when ventilation is poor.
- Optional RH is used as supporting evidence. A single RH reading may miss spikes, so it is weighted less than direct moisture indicators.
- The tool errs on the safe side: visible growth or flooding should trigger urgent action regardless of the RH reading.
What This Score Does Not Claim
- It does not diagnose mold species, health effects, or structural damage severity.
- It does not assume RH alone is enough to confirm or dismiss a serious moisture problem.
- It does not replace professional assessment after flooding, widespread visible growth, or persistent building-water intrusion.
Frequently Asked Mold Risk Questions
At what humidity does mold start growing indoors?
Mold growth generally becomes likely when indoor RH stays above 60% for days at a time. Keep living spaces at 40-55% RH, and address the moisture source if surfaces stay damp regardless of the air reading.
Does a dehumidifier kill mold?
No — it removes the moisture mold needs, but it does not kill existing growth. Visible mold should be cleaned or remediated, and the underlying moisture source fixed, before a dehumidifier can hold the space stable.
What are the first signs of a mold problem?
Musty odor usually appears before visible growth. Watch for recurring condensation, water stains, bubbling paint, and damp spots that never dry. These signals matter even when the RH reading looks normal.
Sources & Methodology
Last reviewed: 2026-08. Information is periodically reviewed and updated as standards, testing procedures, and field data evolve.