High humidity can produce tremendous damage in a home or building. In part 1 of “High Humidity And Mold” we explained the principle of the relative humidity and the relationship between humidity and temperature. In this segment we describe various situations that could lead to high humidity and mold. We reiterate that the relative humidity (RH) should be kept below 60% at all times.
With plumbing leak problems, the water damage and mold develop at a particular location – the sheetrock is progressively saturated with water and mold sets in on the sheetrock, wood studs, and anything in that location. With high indoor humidity the mold spores settle and grow on all surfaces. It starts on surfaces with a haze and progressively the surface mold gets worse and permeates the surfaces and materials.
Early clues about high humidity:
- The occupants describe the air as “clamy”.
- They notice mold-like substance on furniture and clothing.
- They notice mold-like substance on air vents.
Some HVAC thermostats are equipped with a reading to show the relative humidity. Check it regularly. If the humidity starts rising, it’s time to call an HVAC professional. If the HVAC thermostat does not have an RH reading, a humidity/temperature pen, similar to the picture above, can be purchased through our trusted resources. Having a portable pen is very useful to check all the rooms in your house, and it helps locate a potential humidity problem before mold develops.
Some conditions that create high humidity:
There are various situations that can create high humidity in a home or building that result on mold growing on furniture, clothing, and all surfaces. The following are examples:
The HVAC system is designed to help remove excess moisture from the air and keep the RH ideally between 40 to 50%. Some of the humidity problems associated with the HVAC system are:
- An old system can no longer operate efficiently and needs replacing.
- The coils of the air handler may be dirty, usually caused by the lack of filters or improper fiberglass “see-through” filters.
- HVAC thermostat improperly located in relation to the return air register.
- The thermostats of 2 HVAC are improperly placed next to each other.
- Addition of one room with inadequate ventilation provided by the duct system.
The high humidity in closets is mainly due to poor ventilation, or being too cold.
- Lack of an air vent.
- Closet inside a bathroom where the humidity is high.
- Closet near a bathroom where the occupants fail to use the exhaust fan or open the window when taking showers.
- Cluttered closet and plastic bags against the walls.
- Closet being too cold.
Bathrooms provide a perfect environment for mold. The high humidity caused by daily baths and showers, coupled with skin cells and body oils (mold food) makes a bathroom a spa for mold. Mold will settle in and deteriorate grout, caulking, paint, and sheetrock. The main problem comes from occupants failing to use the exhaust fan or open a bathroom window when taking a shower.
High humidity in homes and building will lead to mold if not corrected in time. To avoid the above problems and control humidity, we recommend reading our post “Home Maintenance To Prevent Mold.”