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Best Relative Humidity in Your Home

We frequently hear from homeowners seeking answers to repair and maintenance problems. Many of these questions and answers are compiled in our Home Improvement Library. Here is a recent question.

What is the recommended range for relative humidity inside the house? And where can I buy a humidity gauge and what is the best way to use it?

We recommend a range of 30% to 50% of indoor relative humidity for comfort and health.

Below 30% relative humidity begins to dry out our nasal passages and sinuses which can lead to more colds and flu susceptibility. If you have any sort of respiratory issues, your physician may have a more appropriate range for unique health and comfort.  Too dry can also cause problems to the structure of your home, including cracking drywall and plaster, shrinking hardwood floors, separating trim, and cracking wood furniture and cabinetry joints.

When indoor relative humidity goes above 50%, dust mites and other insects begin to thrive. High humidity also promotes mold and mildew growth which can adversely affect your health.

Like our bodies, a house has its own range for optimal comfort and performance. Fortunately, it is in the same 30-50% range.

Finding & Using a Humidity Gauge

Radio Shack is a good source for battery-powered digital thermometers with a humidity read-out.

Set the thermometer in various rooms of the house, and at various heights. For example, place it on the floor, a table top and about 6’ above the floor for a few minutes each to get a reading. This gives you an average of how well the supply and return ductwork is providing an even heat or cooling in each room and its relative humidity.

If you find a room with unusually low humidity, you may have your explanation for static electricity and sinus problems. If you find a room with unusually high humidity, look for sticking doors or a leak or condensation along the ceiling line or exterior walls. At Mosby Building Arts, we use an infra-red thermal sensing camera for a quick condensation check. It senses temperature differences along walls which indicate insulation voids and the probable presence of moisture. This is a routine part of our home energy audits.

Please feel free to contact us for help with monitoring and correcting indoor relative humidity problems. Call the Mosby office at 314.909.1800 or contact us here.