Humidity’s Effect on Air Control

Maintaining great air quality in your home is possible in every season if you keep in mind two key strategies: simple home maintenance and a waterproofed basement.
A recent TV report stated that Americans spend at least 90% of their time indoors. Yet, indoor air quality is typically 3 to 4 times more polluted than outdoor air, due to insufficient ventilation and excessive moisture content throughout the house.
Two areas in your home that absolutely require ventilation are the attic and the basement (or crawlspace). Other recommended areas are the kitchen and bathroom, by using exhaust fans. If your kitchen and bathroom have windows, open and close them as often as possible (something homeowners seem to rarely do these days).

Maintaining moderate moisture levels in your home is primarily accomplished by rainwater and melted snow and ice running off your roof and down the rain gutters and siding.
We have three seasons for humidity control: 4 months of the heating season (Nov, Dec, Jan, Feb); 4 months cooling season (May, Jun, Jul, Aug); and 4 months venting season (Mar, Apr, Sep, Oct), when little heat or A/C is used. During heating season, the best way to maintain comfortable relative humidity is Passive Moisture Generation through showers, dishes, laundry, houseplants, etc. Setting a central heating system’s mechanical humidifier above +25% ambient can cause excessive condensation (dew drops) in pre-1970s empty side walls and under-insulated attics. To control humidity in the spring and fall venting months, keep windows open, and ensure your rain gutters aren’t clogged.
Portable basement dehumidifiers are ineffective, according to the manufacturer, unless the exterior temperature is above 65° and the unit is set in the center of the room. Moisture is only an issue at above 60% relative. Dehumidifiers set lower than 50% use excessive energy and may run continuously, causing heat build up or even a fire.
Most basement air ducts are not foil-taped and mastic-sealed. This causes, on average, 20% to 35% of the duct air to leak into the basement. During the heating and A/C seasons, this actually helps control humidity.
Foundation leaks that cause a wet basement make the humidity go off the scale in any season. French drains and sump pumps only work when they are mud-free and flowing.
So what’s the best way to have great air quality? By keeping basements dry and vented, using kitchen and bathroom fans, and fully functioning rain gutters.
Hey! Grandma was right when she insisted on emptying kitchen trash before sleep-time and getting a fresh start every day by pulling open the drapes and cracking open the windows!