Optimum Humidity? How to Achieve?

last year

last modified: last year

We live in the southeast. Outdoor humidity can be very high in the summer and very low in the winter. Regardless of time of year, the humidity can vary quite a bit from week to week, even day to day.

The humidity inside our house has been in the range of 35% for over a month due to very cold/dry weather conditions. We are experiencing gaps between boards in our newly installed 3/4" oak flooring. Gaps in crown moulding joints are appearing. Doors are beginning to catch/drag at the corners.

What is the optimum humidity level for a house? The standard is apparently 70 F and 50% humidity. It seems like a whole house humidification and dehumidification system may be needed to maintain the humidity at a constant level.

For reference, we have an AprilAire dehumidifier in the crawl space only. The crawl space is enclosed/sealed with a poured concrete floor over a vapor barrier. The crawl space dehumidifier runs regularly in the summer but hasn't been active during the winter. The crawl space humidity has been about 45% in recent weeks.

Any comments suggestions about humidification and dehumidification are appreciated. We're considering AprilAire steam humidification and AprilAire whole house dehumidifier added to the HVAC system for the house.

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Comments (4)

rwiegand
last year
If you can stay in a 40-60% range, not counting outlier peaks on very wet days, your flooring and such will probably fine-- that will cost you probably 1/10th of what nailing 50% year round will cost.

If you are in the southeast and experiencing extreme dry in the winter you might check the air sealing in your house. Blocking excess flow will tend to raise your indoor humidity in winter as well as significantly lowering your heating bill. Similarly in summer it will help to stop intrusion of very humid air.
nvestysly thanked rwiegand
sktn77a
last year
Dry interior air in the winter is very dependent on air infiltration (most households put plenty of moisture into the home from cooking, perspiration, etc). Check that first.

For humid air in the summer, check if your AC can be run for better dehumidification (usually need a thermostat and air handler that can slow down the fan speed 10-15%).
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vinmarks
last year
last modified: last year
We live in NC. We have a dehumidifier on our walk out basement unit and a portable unit for our main floor. We use portable humidifiers in the winter. I prefer portable humidifiers because i can keep them clean where as whole home units make me nervous that mold will build up in ducts etc. Last week the humidifiers were constantly going. This week they are off. We have warmer temps, rain and higher humidity outside which means higher humidity inside. Current humidity on main level is around 49%. It goes higher when we are cooking.
nvestysly
Original Author
last month
Following up... We installed an AprilAire model 800 whole-house humidifier in the HVAC system. The heating element is 240V (recommended by the HVAC contractor). The humidity is set via the thermostat. Last season (2022-2023) it kept the house at 43% (or so) humidity. I noticed this season that the thermostat was set to "feels like" rather than actual temperature. When I changed to actual temperature the humidity bumped up to about 46%. Minor change but I'd like it to be closer to 50%. There has been a day or two during the 2023-2024 winter season that the humidity did register 50%. Guess that's as good as it gets as they say. Having the humidifier installed has definitely reduced my chapped hands and lips. Time will tell if it's better (or worse) for the house. So far, we like it.