Moisture readings above 90% are a cause for immediate concern as they indicate a very dangerous moisture environment that can lead to a variety of health risks and property damage.
Moisture readings are typically taken using a moisture meter, which measures the amount of moisture in a material or environment. A bad moisture reading is any reading that falls above 30%, as this indicates a high level of moisture that can cause problems. Moisture readings above 90%, are considered extremely high and indicate a very dangerous moisture environment.