Balancing Humidity with a Hygrometer and Whole-House Humidifier

Rooms so dry your hair stands on end? So clammy the walls are sweating? An inexpensive hygrometer will help you maintain proper humidity levels.

If condensation collects on your windows, it's a sign your indoor humidity level is too high. Image: Danielclauzier/Wikipedia

Household humidity: too little of it and you’ll zap your dog with an arcing blue spark when you touch his nose; too much and your carpet starts sprouting mushrooms. Equipped with a hygrometer to measure humidity, you can assess your needs and choose from a wide variety of tools for controlling household humidity.

Size up your personal discomfort level

Your own discomfort is the first clue to an improper humidity level. Here are symptoms to watch for:

Low humidity:

  • dry skin, chapped lips           
  • static cling; sparks zap your fingertips when you touch metal or damp objects
  • irritated nose and throat

High humidity:

  • clammy feeling, especially when wearing synthetic materials
  • allergic reactions, such as sneezing, itchy eyes, and chronic coughing

Look for your house’s symptoms

The amount of moisture in the air doesn’t only affect humans; your house may be suffering too. Here are signs to look for:

Low humidity:

  • Dust buildup   
  • Dried-out, loose furniture joints
  • Moldings, such as baseboards and crown moldings, separate at joints

High humidity:

  • Condensation on the inside of windows
  • Mold on walls and ceilings
  • Insect infestations

How to check your household humidity

A simple instrument called a hygrometer measures the amount of water in the air in terms of relative humidity (RH). Choose from mechanical hygrometers ($5–$35) or electronic types ($8–$25). Locate your hygrometer in a living area away from the moisture produced by the kitchen or a bathroom.

For maximum heating effectiveness and comfort, humidity levels should be between 30% and 50%. In the summer, a maximum of 55% is tolerable. Anything under 30% or over 60% will be uncomfortable and potentially damaging to your home.

Countering dry air

Overly dry air has a chilling effect because it boosts the cooling power of normal perspiration. Get your humidity level right and you can dial down the thermostat a few degrees and feel just as warm. You’ll boost your heating energy efficiency by 1% for every degree you dial down — a sizeable cost savings over the course of the winter.

Options for increasing humidity include:

  • You can boost the comfort in a living area or bedroom with a portable humidifier. Cost: $27–$181.
  • Add a whole-house humidifier to your furnace. It comes with a built-in humidistat that automatically cues the unit to produce the right amount of moisture. Some systems include an outdoor sensor that factors in air temperature. Steam versions are the most effective. Cost: $600–$1,200, installed.

Dealing with too much humidity

If you live somewhere with hot, humid summers, a central air-conditioning system can help keep humidity under control – AC systems remove excess water as they cool air.

However, homes that have basements, below-grade living areas, or are located in coastal regions may encounter high humidity problems year-round. Here are options for reining in the damp:

  • Buy a portable dehumidifier to cope with isolated dampness. Cost: $190–$350.
  • Equip your bathroom with a vent fan. Cost: $25–$100, $235–$527 with an energy-saving heat exchanger.
  • Increase your anti-moisture power by installing a dehumidifier in your HVAC system. Automatic sensors detect humidity levels in the air and adjust accordingly. Cost: $2,000–$3,000, installed.

High humidity in new construction

Newer homes in high-humidity areas are especially susceptible to excess interior moisture because they’re tightly built: air leaks are rare. However, that efficiency can cause humidity buildup.

To counteract, add a heat recovery ventilator (HRV) to your HVAC system. It refreshes interior air and removes humidity without loss of heat. Cost: $3,500 on new construction, $4,500 for a retrofit.

Good exterior maintenance: a line of defense

Be sure to prevent excess moisture from getting inside your home:

  • Check flashing around windows and doors.
  • Use downspout extenders to keep water away from the foundation.
  • Make sure window wells are covered so they don’t accumulate rainwater.