r/Lawrence • u/Reasonable-Hurry6810 • 2d ago
Basement humidity levels
Do you have a finished basement? If yes, do you measure the moisture levels? What is it typically during summer? Ours is around 60-65 during the day and I’m told we have a moisture or drainage problem but I’ve asked a few friends and theirs are also in the 60s. Thought I check here too!
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u/Waldy2024 2d ago
OP: You need a dehumidifier, set to ~50%RH.
Also see if your gutters are not draining well away from the foundation. And seal up cracks.
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u/cyberphlash 2d ago
Typically, you want summer basement humidity to be 40-50% (higher than 50% starts to risk mold development), and in the winter 30-40% to avoid frost on windows at higher humidity levels. When it's very cold out (like lower than freezing) you'll see frost start to form at lower humidity levels. I run a dehumidifier all the time set to turn on over 40%.
See more info here on humidity targets based on external temp.
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u/Reasonable-Hurry6810 2d ago
Thanks for the info. Curious, you run your vent on “on” or “auto” mode? Mine is always on otherwise upstairs will be hell. Could this be the culprit?
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u/cyberphlash 2d ago
When you say "run your vent", what do you mean? I run my dehumidifier in the basement furnace room on auto set to 45%, so whenver the humidity goes over 45%, it runs.
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u/MannyDantyla 2d ago
We got a dehumidifier and I put it at 60% but my wife keeps turning it down to 50% which means it basically runs 24/7 and it also heats up the air a little so when it’s running that much it will heat up the basement about 5-10 degrees. In other words, it should be kept at 60%.
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u/Money-Pain-644 2d ago
Definitely want to make sure your gutters are running away from the house, at least 6 feet. Then you want to make sure your dirt around your foundation slopes down and away from the house, not dipping into the foundation.
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u/RandomUser3777 2d ago
If the upstairs humidity is say 50% (or more likely 55%) and the basement is a few degrees cooler then the same air from upstairs in the basement will have a higher relative humidity. This is why the relative humidity is higher in most cases and most people don't understand this so believe there is an extra source of moisture causing the higher humidity. 75F @ 55% relative humidity is a dew point of 57.7, at 70F that same air at a dew point of 57.7 is a relative humidity of 65%.